Depending on the module you need, you can (use lib) to the dir you want to use. I use it for Statistics::Lite in my own directory.
However, this only works for you if you have Perl-only modules, that don't need to be compiled and installed on the system you're using.
If you use modules like PDF::API2, your isp has to provide them.
"We all agree on the necessity of compromise. We just can't agree on when it's necessary to compromise." - Larry Wall.
No, you can install modules that require compilation without any special access, as long as your Web hosting provider has a compiler installed. The standard module installation procedure will do this automatically; see my other post for what to do if you don't have shell access.
I've probably used about a half-dozen Web hosting providers for various projects, and all but one has had a compiler available (though maybe not all had it available intentionally). So definitely YMMV.