Conversion tracking with installer inbetween?

Good afternoon, I’m trying to get my head around how to successfully use conversion tracking for our websites that offer the user a free download. The conversion needs to occur after the installation has completed. However I can’t for the life of me see how to pass the information obtained at the landing page (ad clicked, keyword used etc…) onto the final thank you page that launches within the installer… otherwise within the Adcenter panel all I can see are which ads are being clicked but no information at all as far as which are converting!

The process is the following:

1. User visits the landing page
2. Downloads the free software
3. Installed the software
4. Thank you page is internally launched.


The company we are working with has mentioned about creating a custom parameter for us and have asked me where about in the pixel should this parameter be placed, however from what I can see, the conversion pixel cannot contain any custom code? The only options I see for adding custom options is in campaign analytics where you add goals and dimensions… aside from this there is an option to add custom string queries to the destination URL.

Any help would be greatly appreciated!
Cheers,
Lee.