CMS page friendly urls map to the real url /Default.aspx?pageid=x
You should not pass extra paramters to CMS page friendly urls and you cannot make friendly urls that point to other friendly urls.
You should build a custom feature with a supporting page instead of trying to do everything in the module control on the CMS page. The module control is the entry point for your feature but for complex features you need to use supporting pages.
The real url for your supporting page would be formatted as /featurefolder/yourpage.aspx?pageid=x&mid=y&agentid=z
Then you can programatically create friendly urls that map to your real url
This is exactly how the blog works, the blog detail is really:
but when posts are created we programatically create friendly urls, the friendly url is also stored on the blog itself so that we can build links to the friendly url pages within the blog.
Study the source code of the blog and webstore which also uses friendly urls for products to learn how to implement it for your own feature
Hope that helps,