When you have the solution open in Visual Studio, click the find in files button at the top. Search for 'perl510' without the '. If you did it right, you'll see 2 lines:
Code:
C:\EQEmu\ServerCode\trunk\EQEmuServer\world\EQWParser.cpp(42):#pragma comment(lib, "perl510.lib")
C:\EQEmu\ServerCode\trunk\EQEmuServer\zone\embperl.cpp(33):#pragma comment(lib, "perl510.lib")
Change perl510 to perl512 or whatever version you installed.