apache checkout common conversion converting domain google javascript optimize page particular register rewrite successful successfully thank-you-page

In particular, the page with the checkout for EJ is the page I want to optimize.

For it to register a successful "conversion" I need to put some kind of Google Javascript on the converting page.

I tried to use the common EJ Thank You page, but the conversion page needs to be of the same domain.

1) has anyone done this successfully?

2) would an apache rewrite to the thank you page work?

3) Other ideas?

Thanks!