Usuaully one should not use regexp try to parse html, but in this particular case, it is just fine to use simple regexp to locate what you are looking for in the files - and this way, you don't need to install extra packages.

Assume that you have used regexp in C#, you wouldn't find any issue to use the perl one.

The other thing you need is File::Find, so that you can traverse the directories.

Since you have already done lots of research, just do a little bit more, and focus on regexp and File::Find.