you just need to find a socket for the input shaft surronding ring thing (don't know what it's called though)
once thats sorted you just undo the bolts around the outside of the centre line, one that holds the reverse gear idler cog and then just prise them apart
BUT
you will need to remove the cogs to swap over the input shaft so it's not as simple as you might think
i'm sure someone will come along with the corect sized socket you need, but when i enquired about getting one i was quoted £300 so i used a screwdriver as a drift and a hammer to knock it round via the clutch lever hole in the bellhousing