Depends on how long she is away from the flock--the longer the time, the more difficult it could be. I've got some tips on my chicken site, here:
http://jackshenhouse.com/VSChickIntroducingNewBirdsToFlock.htm

I'd start with a couple of short, supervised outings of about 20 minutes each, so the other birds can see her and realize she's back--but while you are nearby to protect her and shoo away any bullies. Then you could go with stuffing her in amongst the others after dark so they all wake up together.

Expect SOME pecking and squabbling, you can't eliminate it all, just hopefully lessen it a bit.

She should soon resume her old place in the pecking order.

Velvet ~:>

Thanks for the tips. Hopefully it'll go fairly smoothly!