If the home grown modules will never see the light outside your company, simply put the modules in your company's namespace. For example, Loony Tunes could be LoonyTunes::Monitoring::Coyote::RoadRunner

Whether you want to create the modules using one of the myriad of CPAN ways or just put them in a directory (adding to PERL5LIB or "use lib ...") is purely up to you :)