Millisecond Forums

I am running a web script. I want participants to manually enter their IDs. I also want to send a "session ID" through the URL, e.g.,

http://research.millisecond.com/example/myexperiment.web?sessionid=1

Can I do this? Will it be recorded? And, more importantly, can I access that info in the script? I'd like to be able to say "present stimuli from this list for session 1 but this other list for session 2." Seems pretty easy, but I can't figure it out.