9 bolt steering wheel

[BERGS2]

I have an S2 with the old school style wheel - 9 raised allen bolts around what looks like a horn push but is curiously empty....

I want to fit a three spoke wooden wheel with the 6 countersunk screws - like this:
www.pistonheads.com/tvr/s/Default.asp?storyId=3273

does anyone know which bits will need to be replaced?

is there an adapter or will I have to get the boss off the column?