is it possible to insert a CGI script (using Server Side Includes) directly into the source code of a PHP webpage?
Yes jay. I do this with my PHP pages. I have a cgi script that keeps track of the number of visitors. I simply do an 'include' for the cgi script call.
include("http://www.mydomain.com/cgi-bin/guests.pl");
Oops... you said insert using server side includes didn't you. Well, I don't know how to do that, but my previous example works just fine without SSI. In fact, I can use that script within SSI or PHP using an include.