Copy and paste works in Illustrator or Photoshop. I don't know if it would work in Nuke or not. Vector paths in AE are in the AICB form preserving paths.
I know of no other way to move paths from one app to another.
Thanks Rick. Hm... seems promising that if it's copy-paste-able there could possibly be a way to parse it into a useable format. Still open to more suggestions if anyone has them.
Probably something that could be done with a Python or TCL script in Nuke by pasting the data in a respective field in a node. Otehr than that you could write the mask data to an intermediary text/ XML file with a script from AE and then parse the info back into Nuke using anotehr script there...
Thanks for the suggestions. What I ended up doing was outputting the mask points/animation in literally a .nk file syntax so the end result was essentially a rotopaint nuke file. I used rotopaint because I was using autotrace which caused each frame to have different numbers of verts. Unfortunately only once I got it working did I realize that it caused nuke to go terribly slow.