I don't think there are many Ngage users here from what I gather, you'd probably be best asking in one of the many Ngage forums, maybe http://www.ngage-user.com/ forum is worth a try. I know it can be done but I couldn't tell you how as I haven't tried arena yet myself, that might change with the release of Pathway to Glory though
One thing I'm pretty sure of, you'll need a bluetooth dongle for that connection.
BTW, have you seen the screens for Requiem of Hell yet? looking like a cool game for the Ngage