Django admin interface: using horizontal_filter with inline ManyToMany field

I have a Django model field that I'd like to inline. The field is a many-to-many relationship. So there are "Projects" and "User profiles". Each user profile can select any number of projects.

Currently, I've got the "tabular" inline view working. Is there a way to have a "horizontal filter" so that I can easily add and remove projects from a user profile?

Please see the attached picture for an example.

Here's the model code for the User Profile:

class UserProfile(models.Model):
    user = models.OneToOneField(User, unique=True)
    projects = models.ManyToManyField(Project, blank=True, help_text="Select the projects that this user is currently working on.")

And the model code for a Project:

class Project(models.Model):
    name = models.CharField(max_length=100, unique=True)
    application_identifier = models.CharField(max_length=100)
    type = models.IntegerField(choices=ProjectType)
    account = models.ForeignKey(Account)
    principle_investigator = models.ForeignKey(User)
    active = models.BooleanField()

And the admin code for the view:

class UserProfileInline(admin.TabularInline):
    model = UserProfile.projects.through
    extra = 0
    verbose_name = 'user'
    verbose_name_plural = 'users'

class ProjectAdmin(admin.ModelAdmin):
    list_display = ('name', 'application_identifier', 'type', 'account', 'active')
    search_fields = ('name', 'application_identifier', 'account__name')
    list_filter = ('type', 'active')
    inlines = [UserProfileInline,]
admin.site.register(Project, ProjectAdmin)