All done, thanks to p carr for his advise on this one.
gonna put up some piccies to show how i did it.
first up, jack up rear end and place on axle stands
remove dust caps to torsion bars
rig up homemade torsion extractor tool as shown
http://www.btinternet.com/~weightspalace/drop/MVC-001S.jpg
install extractor tool and tighten up the bolt only into the torsion bar
then start to unwind the nut untill the socket starts to pull on the torsion bar housing
http://www.btinternet.com/~weightspalace/drop/MVC-002S.jpg
also at this time i made a note of the floor to centre hub dimension
start to unwind the nut fully, which inturn pulls out the torsion bar
http://www.btinternet.com/~weightspalace/drop/MVC-003S.jpg
http://www.btinternet.com/~weightspalace/drop/MVC-004S.jpg
with torsion bars removed both sides, clean and grease the splines
http://www.btinternet.com/~weightspalace/drop/MVC-005S.jpg
place a jack under the rear arm and lift the arm untill the toothed bracket in the centre of the car has rotated just one extra spline than standard. this will take some time to get everything lined up, take your time and keep adjusting the arm up and down if necessary untill the toothed bracket and torsion bar line up.
http://www.btinternet.com/~weightspalace/drop/MVC-007S.jpg
with one torsion bar inserted remeasure the ground to centre hub dimension.
if you have done this correctly it should be 30mm more than before.
http://www.btinternet.com/~weightspalace/drop/MVC-008S.jpg
then measure the the other side without the torsion bar inserted. hopefully again it should be 30mm higher than before. then insert the torsion bar making sure you still have that extra 30mm hieght.
http://www.btinternet.com/~weightspalace/drop/MVC-006S.jpg
make sure both sides are knocked fully home. i used an upturned socket and hammer to do this.
replace dust caps
check everything
http://www.btinternet.com/~weightspalace/drop/MVC-009S.jpg
http://www.btinternet.com/~weightspalace/drop/MVC-010F.jpg