Thats what the trailing lead is for. Get some fairly heavy cable (i.e. >2.5mm2) and clamp one end to the battery -ve using vice grips, then connect the other end to the multimeter -ve cable.
SOOOOOOOOOOOOOOOOOooooooooooooooooooooooooo
What my mechanic supposably did to get her going,
Connected a 0 gauge, from block to rail.
And apprently the dizzy was out 180, BUT that cant relly be right, since we turned it fully clock wise, and anti clock wise basicly tried it everywhere with no luck.
So for future reference for anyone who does a search on this subject, as per my posts in this (http://www.calaisturbo.com.au/showthread.php?t=175073) thread, it is vitally important that an earth cable is ran directly from the block to the -ve terminal on the battery. Relying on the body as an earth path for a starter motor drawing 100A is poor form.