What exactly do you have in mind? To convert the POD documentation of the modules installed at your machine into plain text, you just need perldoc. For example, converting the DBI docs into a text format:

$ perldoc -t DBI > DBI.txt
[download]

You may use pod2text as well, but in this case you have to find the full path of the file.

$ perldoc -l DBI
/usr/local/lib/perl/5.8.8/DBI.pm

$ pod2text /usr/local/lib/perl/5.8.8/DBI.pm > DBI.txt
[download]

Converting from PDF or something like that will probably be much poorer than the approach above that generates plain text from POD sources. If you want to convert many perldoc pages, writing a script to do that (as appropriate to your needs) should not be hard.