DS9's "Paradise" (s2 e15) has one Runabout tractoring another (running on automatic) at warp. It was, however, at fairly low warp, and Kira was worried about the possibility of both ships coming apart under the strain!
Why they couldn't just hack in through the security codes, I don't know
Jon
"There are worlds out there where the sky is burning, where the sea is asleep and the rivers dream; people made of smoke and cities made of song.
Somewhere there's danger, somewhere there's injustice, and somewhere else the tea is getting cold. Come on, Ace, we've got work to do."
THE DOCTOR, "Survival" (Doctor Who)