two ways come to my mind: one is simplier but requires C, another pure-perl but harder.
create a simple C wrapper program that takes one argument - DLL file, and then, using API calls (FindResource and such) performs the trick. Use this program from Perl.
Use MS Visual Studio, use Win32::OLE and control it to open DLL file and save it as resource. You will get text file containing your string table
I was requested to write such a program at work, but I switched to other tasks for some reason, so I don't have code.