If there's a ruby/node.js/perl6 kernel running, the qtconsole should select the matching lexer to color the code accordingly.
Do you have a link to the perl kernel ?
At the moment it's just a very, very ugly piece of python code that talks to rakudo via Popen, but I'll first make a new REPL that talks a wrapped json protocol with a slightly less ugly piece of python code and when Net::ZeroMQ is ready, I'll turn that into a perl6 module and have it all in one process.
If you really want to look at the code, I won't stop you, only warn ;)
Great, I suppose you had a look at #2643 :-)