Set window onload to call a function. This would tack a '?' and the variable (having escaped it) onto the end of the cgi filename. Call the script.
'javascript tutorial window.open' would give you a good start.
wfsp

update:
I've posted a script you could use in the question you posted to devshed.
Thankfully, it is very similar to the other reply. I'm not completly mad yet!
Apologies to all for any OT infringments
wfsp