XML::Parser is an XS module, and it creates .so files when you compile it. You can't install a module requiring compilation on a remote machine you have no command-line access to, unless you can compile it locally and then upload all of the .so files too, and even then you might have to adjust the library path. If you do have command-line access, you can compile it there and install it locally. You can find instructions for doing this by searching on this site.

Why don't you ask your ISP if they'll just install XML::Parser for you? It's a pretty common module and a reasonable thing to expect an ISP to support.