Any small vacum hose that is coming from engine side of the throttle assemblynot the intercooler side.
On the 99/00 manifold there is a spare nipple just in front of the throttle.
I think for the 97/98 you need to T into one of the existing 3mm hoses in that area.
This image is for a 1996-1996 but you get the idea :
http://www.scoobymods.co.uk/boostg01.htm