rewrite/redirect problem

[m94asr]

Hi,

I get requests that look like

/m?http://i.abc.com/A/P?vcode=bz==&p=uid:$DFG

I can't change the format in which I get these requests;

I want todo a redirect to what I have in $args, but $DFG should get
replaced with a value I have in another variable ($uid, from
httpuserid-module).

so, if $uid is 42, a redirect to e.g.
http://i.abc.com/A/P?vcode=bz==&p=uid:42

Sounds simple, but I can't get it to work.

Thanks for helping,
  -Armin Roehrl