I did a similar approach (I thought about posting this hint, but obviously I was beaten to the punch), but used the source code importer in /Library/Spotlight. All you need to do is add the file extension to the info.plist entry under CFBundleDocumentTypes > 0 > LSItemContentTypes. Just use the New Sibling button and under value, type the extension (I added .cgi, .pl, and .pm entries). Now Spotlight sees and indexes all my Perl stuff. You can add any other type of plain text extension, which makes this much more effective than the original hint here.

I actually tried the source code importer first, but it looks like it's made specifically for C/C++/ Objective C/C++ and I'm not sure how it's going to behave with other languages. I think the plain-text importer is safer.