You actually have to disconnect the linkage to take the gearbox out as it is connected to both the box and the body. It would be easier to do with no exhaust or prop shaft but removing the heatshield under the prop gives you enough access.
To remove the linkage rod and the shift rod link:
1. Remove the 4 bolts holding the heat shield on, 8mm socket
2. Remove the shift linkage, the clips push off by hand.
3. Remove the shift rod link, the retaining collar is a pain to push off, needs a short screw driver and the pin needs to come out downwards, mine was loose enough that a bit of wiggling caused it to fall out by gravity.
To remove the gear lever:
4. Remove gearknob, 3 grub screws
5. Undo the single nut at the rear mount to the body, 13mm socket UJ and very long extension
6. Undo the bolt at the front mount on the gearbox, 17mm spanner and 10mm socket
7. Withdraw the bolt from the front mount, up until this point it hadn't been too hard but getting this bolt out took almost 2 hours as it was welded to the rubber bush and there's not a lot of room to lever, a good soaking with WD40 helped.
8. Slide the rear mount forwards to detach from body pins and pull front mount out of gearbox, you can now detach the rubber grommet in the transmission tunnel and pull the whole thing down.
It is however really fiddly and not easy without a lift, if someone said they'd do it for me for £100 labour I'd say yes.
I'm going to order a new shift rod link from BMW tomorrow (£35 instead of £320 from Maserati), I've ordered a poly front bush from Powerflex (BMW E30 £16), a new plastic ball carrier (£9 wasn't noticeably worn but while I'm there..) and a new rear mount from Eurospares (strangely enough they list it at £10 and BMW want £70)