Install a .NET windows service without InstallUtil.exe

Yes, that is fully possible (i.e. I do exactly this); you just need to reference the right dll (System.ServiceProcess.dll) and add an installer class...

Here's an example:

[RunInstaller(true)]
public sealed class MyServiceInstallerProcess : ServiceProcessInstaller
{
    public MyServiceInstallerProcess()
    {
        this.Account = ServiceAccount.NetworkService;
    }
}

[RunInstaller(true)]
public sealed class MyServiceInstaller : ServiceInstaller
{
    public MyServiceInstaller()
    {
        this.Description = "Service Description";
        this.DisplayName = "Service Name";
        this.ServiceName = "ServiceName";
        this.StartType = System.ServiceProcess.ServiceStartMode.Automatic;
    }
}

static void Install(bool undo, string[] args)
{
    try
    {
        Console.WriteLine(undo ? "uninstalling" : "installing");
        using (AssemblyInstaller inst = new AssemblyInstaller(typeof(Program).Assembly, args))
        {
            IDictionary state = new Hashtable();
            inst.UseNewContext = true;
            try
            {
                if (undo)
                {
                    inst.Uninstall(state);
                }
                else
                {
                    inst.Install(state);
                    inst.Commit(state);
                }
            }
            catch
            {
                try
                {
                    inst.Rollback(state);
                }
                catch { }
                throw;
            }
        }
    }
    catch (Exception ex)
    {
        Console.Error.WriteLine(ex.Message);
    }
}

Take a look at the InstallHelper method of the ManagedInstaller class. You can install a service using:

string[] args;
ManagedInstallerClass.InstallHelper(args);

This is exactly what InstallUtil does. The arguments are the same as for InstallUtil.

The benefits of this method are that it involves no messing in the registry, and it uses the same mechanism as InstallUtil.

Here is a class I use when writing services. I usually have an interactive screen that comes up when the service is not called. From there I use the class as needed. It allows for multiple named instances on the same machine -hence the InstanceID field

Sample Call

  IntegratedServiceInstaller Inst = new IntegratedServiceInstaller();
  Inst.Install("MySvc", "My Sample Service", "Service that executes something",
                    _InstanceID,
// System.ServiceProcess.ServiceAccount.LocalService,      // this is more secure, but only available in XP and above and WS-2003 and above
  System.ServiceProcess.ServiceAccount.LocalSystem,       // this is required for WS-2000
  System.ServiceProcess.ServiceStartMode.Automatic);
  if (controller == null)
  {
    controller = new System.ServiceProcess.ServiceController(String.Format("MySvc_{0}", _InstanceID), ".");
                }
                if (controller.Status == System.ServiceProcess.ServiceControllerStatus.Running)
                {
                    Start_Stop.Text = "Stop Service";
                    Start_Stop_Debugging.Enabled = false;
                }
                else
                {
                    Start_Stop.Text = "Start Service";
                    Start_Stop_Debugging.Enabled = true;
                }

The class itself

using System;
using System.Collections.Generic;
using System.Text;
using System.Diagnostics;
using Microsoft.Win32;

namespace MySvc
{
    class IntegratedServiceInstaller
    {
        public void Install(String ServiceName, String DisplayName, String Description,
            String InstanceID,
            System.ServiceProcess.ServiceAccount Account, 
            System.ServiceProcess.ServiceStartMode StartMode)
        {
            //http://www.theblacksparrow.com/
            System.ServiceProcess.ServiceProcessInstaller ProcessInstaller = new System.ServiceProcess.ServiceProcessInstaller();
            ProcessInstaller.Account = Account;

            System.ServiceProcess.ServiceInstaller SINST = new System.ServiceProcess.ServiceInstaller();

            System.Configuration.Install.InstallContext Context = new System.Configuration.Install.InstallContext();
            string processPath = Process.GetCurrentProcess().MainModule.FileName;
            if (processPath != null && processPath.Length > 0)
            {
                System.IO.FileInfo fi = new System.IO.FileInfo(processPath);

                String path = String.Format("/assemblypath={0}", fi.FullName);
                String[] cmdline = { path };
                Context = new System.Configuration.Install.InstallContext("", cmdline);
            }

            SINST.Context = Context;
            SINST.DisplayName = String.Format("{0} - {1}", DisplayName, InstanceID);
            SINST.Description = String.Format("{0} - {1}", Description, InstanceID);
            SINST.ServiceName = String.Format("{0}_{1}", ServiceName, InstanceID);
            SINST.StartType = StartMode;
            SINST.Parent = ProcessInstaller;

            // http://bytes.com/forum/thread527221.html
            SINST.ServicesDependedOn = new String[] { "Spooler", "Netlogon", "Netman" };

            System.Collections.Specialized.ListDictionary state = new System.Collections.Specialized.ListDictionary();
            SINST.Install(state);

            // http://www.dotnet247.com/247reference/msgs/43/219565.aspx
            using (RegistryKey oKey = Registry.LocalMachine.OpenSubKey(String.Format(@"SYSTEM\CurrentControlSet\Services\{0}_{1}", ServiceName, InstanceID), true))
            {
                try
                {
                    Object sValue = oKey.GetValue("ImagePath");
                    oKey.SetValue("ImagePath", sValue);
                }
                catch (Exception Ex)
                {
                    System.Windows.Forms.MessageBox.Show(Ex.Message);
                }
            }

        }
        public void Uninstall(String ServiceName, String InstanceID)
        {
            //http://www.theblacksparrow.com/
            System.ServiceProcess.ServiceInstaller SINST = new System.ServiceProcess.ServiceInstaller();

            System.Configuration.Install.InstallContext Context = new System.Configuration.Install.InstallContext("c:\\install.log", null);
            SINST.Context = Context;
            SINST.ServiceName = String.Format("{0}_{1}", ServiceName, InstanceID);
            SINST.Uninstall(null);
        }
    }
}