I'd prefer not to get Trans'd into the enemy group. Jareth is at his best when he's able to quickly move in and out of the conflict (Spring Attack, with Knock-Down for Trips). He doesn't quite have Whirlwind Attack yet... When he does get that, he'll be more up for the
"Oh, dear, I'm surrounded... Not!" sort of thing.
But sending Mal into the center, with Jareth harrying on the outside of the group, (doing his hit-and-run thing, AoO'ing and tripping anyone trying to close with him) would probably work pretty well. Then Ern would need to join into the formation with the others and everyone else just stay protected. Maybe some magical/ranged attacks, but avoid melee like the plague. Leave the melee stuff to those who are good at it.
BTW, HM, looking ahead to 6th level... I'd like to trade out Spell Power +2 (and it's later enhancements) for Power Attack (and possibly other feats from the PA line, later, if you agree). Jareth's fighting style focuses on inflicting the most damage possible, while staying away from the fray (or overpowering
everyone in the fray - Whirlwind Attack). Power Attack emphasizes that while Spell Power... doesn't.
(Plus, Spell Power is only good against creatures with SR, and it only provides a small bonus. Considering we're likely to be heading into more pitched battles, most soldiers aren't going to have anything resembling SR.

)