Presuming it's really CGI (not FastCGI) you should be able to use the ps command's e flag (again presuming the OS in question's ps supports BSD-y arguments) to dump the process' environment where you'd see things like path info and query strings and what not. You may also find several w's useful to dump more of the environment.
Alternately if the OS supports it and permissions allow it you may be able to extract information from the /proc filesystem (e.g. on Linux you could look in /proc/##/environ).
