There exist modules to combine some combinations of EV, Event and Glib: EV::Glib, Glib::EV and Glib::Event.

Also AnyEvent is a way to write event-loop neutral modules (supporting at least Tk, Glib2, POE, EV, Event, IO::Async and a pure perl event loop). This is similar to how POE::Loop works, but EV is an event-loop of its own. An ugly and hackish way of combiining multiple loops would be to single step through event loop 2's events on event loop 1's idle callback or on a timer (most event loops support processing their pending events one at a time instead of running their mainloop directly).

Update: Another possibility for adding EV loops to other event-loop using modules is EV::Loop::Async, which lets you embed an mod:://EV loop into code using a different mainloop with Async::Interrupt, which allows asynchronous interruption of running perl code with through the signal mechanism.