How to populate a form in POST method

I have a form on a website, where I need to submit hundreds of records, manually. The form is in POST method.

I tried with the simple: http://.../form?incomingLead__email=MYNAME . but this didn't work.

How can I manipulate the Form submission action to include the values?

Trying with a single field as follow: this is the First Name attribute from the HTML:

<input id="incomingLead__firstName" name="incomingLead__firstName" 
class="text" style="" type="text" onkeypress="var _this=this;return 
onEnterPressed(event, function()
{document.controller.setValue('/ctx/incomingLead/@firstName',
_this.value, 'incomingLead__firstName');return true;});" 
onblur="document.controller.setValue('/ctx/incomingLead/@firstName', 
this.value, 'incomingLead__firstName')">

The form attribute is:

<form method="post" name="page" class="main-navigation" id="page-form">

Submit button:

<button type="button" id="link-link330" onclick="return linklink330();">Submit</button>

Validate JS function:

function toValidate() {
  var temp = document.getElementById('temp')
  if (!temp) return document.controller.submit('submit');

  document.controller.setValue("/ctx/vars/iCountProducts", temp.options.length);


  for (var i = 0; i < temp.options.length; i++)
    document.controller.setValue("/ctx/vars/products/product" + i, temp.options[i].value);

  return document.controller.submit('submit');
}

I think of having an excel file, and concatenate the links I need, at least I can reduce the time form filling data, into 2 clicks: one in excel to open the webform, and than submit.

Is it possible with the data given?