You don't have to 'Pull' a hornpipe into 12/8. Any 4/4 hornpipe played with a dotted or swing feel can be notated in 12/8 with ease. Well 'with ease' is kind of cheeky. It's a lot easier to notate a tune in 4/4 and say to play it with 'Swing feel' than it is to notate it in 12/8.

OK in these days of notation editors, I use Musescore, you can notate in 4/4 and instruct it to play with swing feel, or you can notate in 12/8 with no swing instruction and it will sound the same. Notating in 4/4 is easier but you risk losing the instruction to swing and then get people telling you that you are playing it wrong.

12/8 can be two bars of 6/8 joined together. Perhaps it's all down to feel. I have a theory, or perhaps it's just a daydream, that 'hornpipe' was perhaps once an instruction to 'swing'.