cheers vwbusman for this.
I purchased my adjusters from Creative Engineering for £95. They came with a set of clear instructions which are easy to follow and are available on their website creative-engineering.com
A quicky guide:
1. With beam removed, Scribe datum marks to note exact postion of steering mount on lower tube and proceed to grind off steering mount.
2. Drill out the three divets which hold the centre boss in position on both tubes.
3. Mark out slot positions and drill a hole in each tube at the top of each slot using flat bottomed drill bit.
4. Grind out slots with dremel
5. Weld adjusters in position.
6. Weld steering mount back in position. (I also welded a small strip of metal over the divet holes to prevent any water getting in).
7. Refit torsion springs and torsion arms (if you removed them, which I had)
Here's a couple of pic's of my adjusters.
The steering mount bracket removed and the adjusters clamped in position ready for welding

Slots marked out

Hole drilled at top of adjuster slot using flat bottomed drill

Then the slots ground out with dremel

An adjuster welded in position

The beam primed with the steering mount welded back on and adjusters fitted

Sorry I don't have enough pic's to give proper instructions but the creative instructions explain all.
Good luck and let us know how you get on