Update: I need to clarify that I also use this process for internally developed modules, and that the testing phase is absolutely key. Every time I have skimped on testing, I have regretted it.

Many modules don't have current PPMs available. If I should desire to install one of these modules, I follow these steps:

1. Download distribution from CPAN.
2. Unpack distribution to a build directory.
3. Run Makefile.PL or ?? as appropriate.
4. Run make
5. Run make test
6. Run make_ppm from PPM::Make
7. Run ppm install Foo.ppd

I like to stick with one package manager, so I avoid doing manual installs or using the CPAN shell. YMMV.

The last two steps could be condensed into simply running 'ppm_install'.