Not sure which one you are trying to setup or what is involved - but typically calling it in thru an iframe tag would work. You may find this knowledgebase article helpful: http://www.americommerce.com/kb/?f=110
You can start with the above link and if you need assistance, please drop me a line thru the support ticket system. Maybe we can use your setup as an example and create a knowledgebase article with that for future reference.
Thanks,
Manjula