Either do the install offline using PPM and a local, downloaded .ppm file for Tk (Tk), or install a matching C compiler on the target machine. cl.exe is from MSVC, and likely your Perl was compiled using Microsoft Visual C 6, so you need that. You can also try to graft on the MinGW gcc.exe that is distributed with Strawberry Perl. In theory, AS Perl should pick it upo automatically once it finds it available, but I've never tried that.