In Debian packaging (i.e. the debian/control file), is there a way to define dependencies to specific CPAN modules?
You have to make a Debian package for each CPAN module that you need, and declare those as dependencies. The Debian Perl policy (
/usr/share/doc/debian-policy/perl-policy.*) has some information on that. The tool
dh-make-perl automates most of the module packaging work.