It's a bit limiting because you can only ship pure Perl modules that way - or hope that you have a nice server admin who is willing to do it for you.
It's actually not that hard to install compiled modules with only Web access; have an installer script, run from a Web browser, that runs the compiler and installs the modules in the user's home directory. See Re: Re: Alternatives to User::Agent?
for an example; obviously you'd have to adapt this for your purposes. I've found that this works for most Web hosting companies I've used, and I do it frequently.