Wowza has a single connection per protocol per stream to the origin. For this reason there is no way (That I know of) to forward URL params from edge to origin, as it would not be useful.
An alternative would be for you to use IMediaStreamNameAliasProvider using appInstance.setRepeaterQueryString(…..) . Or the default QueryString property in Application.xml to do this:
Take a look at this module as a reference:
How to do user authentication for Flash RTMP client using JDBC connection to MySQL database
I hope this is helpful.