Not sure I understand your question (also you didn't specify your target OS and printing system) , but I find the KDE kprinter program handy. It pops up a dialog where you can choose from different printers / printing systems etc. Just run it instead of LPR (one tip: use kprinter --stdin if you want to send data by piping instead of temporary files as arguments).

Unix: you can always parse /etc/printcap (the Printer module may do it for you, the docs says it does have a list_printers method)

Windows: One quick search on CPAN yields Win32::Printer::Enum, a module that enumerates Windows printers, though I can't recommend it because I never used it.