It'd be doable on the floor but not pleasant. Things I learned:
1, Move the headlight level sensor. Its right in the way of where your arm needs to be. Two M6 socket-head bolts to remove the bracket, undo the connector and release the wiring harness from the bracket and it'll just hang down out of the way:
2, Remove the driveshaft heat shield. Thats also in the way of your arm getting to the top gearbox mount bolt. It needs to be out of the way to move the mount. Already removed in this pic:
3, Move the exhaust. Its not worth trying to work around it - its just too tight. Remove the four bolts holding the downpipe to the n/s cat:
Then loosen the two bottom ones from underneath. You don't need to remove the downpipe, just loosen it so it will twist towards the side of the car by 1", hence you don't need to touch the top manifold bolt. These two can be accessed through the gap in front of the driveshaft:
Note my new stainless fixings which made this very easy for me, whereas old rusty factory nuts could really spoil your day. A 12mm ratchet spanner is pretty useful here.
4, Move the subframe brace out of the way. This is right where you need to be working.
5, The gearbox mount does not need to be split like the Audiworld article says, or even removed completely - just moved out of the way. The gearbox needs lifting to undo the bolts. I used a transmission jack with it up on the lift, but on the floor a trolley jack with a block of wood on the gearbox sump flange will do.
Do NOT lift using the sump!!! Only the flange. You don't need to move it far, just take the weight off the three bolts. The bottom two are easy with an 8mm hex hey on an extension. The top one is much harder but doable. I used the same 8mm hex key on a 3/8" ratchet. There is space above the mount to move the ratchet, putting your arm in from in front of the inner CV joint. Two more bolts hold it to the subframe from underneath.
Once the three bolts are out you can shuffle the mount away from the 'box just enough to get to the switch, and the 'box does just sit there on only three mounts. It only drops a few mm when you take the jack away, but you will need to lift it again to get the mount back in.
6, You need a T27 Torx to get the switch off the gearbox but with the downpipe still in the car a standard 3/8 bit or allen-key type won't fit. I used just the bit from my set with a 10mm ratchet spanner to get in the space.
This tool is key to it being straightforward. Without something like this you'd need to take the downpipe off completely which will be a bit of a 'mare on a car with original hardware and the SAI stuff still in place.