Get URL Parameter javascript.

Javascript - GUP (get URL parameter)
We need some assistance with javascript.
We have recently chosen http://www.emailvision.com as our ISP who provide the campaign commander software to manage our email communications. Within emailvision there is a facility to create a webform using a point and click GUI.

Our aim was to send an email to our customer base to ask them to check the details that we hold on them. They would then click on the webform link within the email which will open a new window (the webform) and to ask them to fill in the gaps (where we hold no information in a field) and to update any existing information if it is out of date.

Unfortunately the EV GUI will only present the recipient with a blank form with all the fields (Title, firstname, lastname, job title, mobile number, email address) all empty. The EV GU does not support pre-population of the fields in the webform with the details in the EV database.

After speaking with EV support, I am told we require some javascript to be able to pull the relevant variables from the URL (which comes from EV) and to populate the correct value in the html field in the webform. This is called a gup (get URL parameter)

So that when a recipient clicks the webform URL they see all the details that we hold on them displayed in the webform in the appropriate fields. They can then update existing information or add any new information as appropriate.

I hope this brief makes sense. This job really needs a self starter (I cannot provide much more detail than the above)

Anyone with experience of dealing with ISP or writing gup in javascript will be at a distinct advantage. We will pay on successful testing of code so a fixed charge for providing the completed code is preferred. Please provide likely timescales also for completion of the code.