Engine stays in situ, but you will want to stick some timber or similar under the front of it to make it easier to re-install the box . Step one is drain the gearbox oil. Depending on model you will need just a nomral spanner/socket or a T70 tork socket- male. Whhile that is draining, remove the tailshaft- there are few bolts you have to undo to access where it bolts to the rear diff. Remove air filter box/TMIC. If turbo begin removing heat shield from turbo, remove O2 sensor- some cars come with more than one sensor- remove it as well. Disconnect battery. Remove dump pipe if turbo. Remove starter motor. Disconnect wiring to gearbox, speedo cable if equipped. Remove slave cylinder. If turbo, there is a hex bolt which requires a 10mm hex key or socket to undo- remove. You cam use a guard bolt or similar to screw that into what is the pivot for the clutch fork. Screw it in a few turns then using pliers,screwdriver or similar and pull the pivot out by the head of the bolt. Ignore that if non turbo. Remove all belhousing bolts. Loosen cotter pin on each front wheel hub and remove hub from ball joint. Depending on model there is a split pin securing the front driveshaft to the output shafts of the front diff. With 6mm pin punch remove the pins and then remove the axles. Hopefully not too much oil will spill out as the gearbox should now be drained. So put the bolt back in you removed to drain. Later, depending on model you may need a washer for the bolt- not used if you used the tork socket.
On the inside of the car, remove the trim around the gearshift and remove the gear knob and boot. You will find half a dozen screws or so holding the rubber grommet-remove. With the normal gearstick there are two bolts/nuts you have to remove to remove that shifter. If you have dual range you will need to undo it at the lever end and at the front of the gearbox as well. Remove the crossmembers under the gearbox. Have a good look around, there should not be anything else left to undo- if there is, remove it. If I have left something out someone will probably pick it up. Make sure there is a jack under the gearbox and secure the jack to the gearbox using chains ( I used a hoist and gearbox jack). You will need to lever the box backwards, and you really should have someone helping you.
With the gearbox out, I use a small 12v rattle gun to remove the clutch from the flywheel. Careful, it is heavy. I then use a big 18v rattle gun to remove the flywheel bolts. Be careful, it is even heavier. If it is a dual mass flywheel replace it with a standard flywheel. If standard flywheel, machine it and re-install. Do not use rattle guns for tightening the clutch bolts. A clutch aligning tool will make life much easier- I used an old gearbox input shaft but you can buy the specialised tool. Line up the clutch, then tighten up to spec. Line up the gearbox so that the angle of the box is the same as the angle of the engine front to back and side to side. This is the hard bit and strength and patience are needed, So is help, although I have installed a 6 speed without any, and did it first go. That is rare and make sure you have bought plenty of swear words in case you run out.
You need a certain amount of force but not too much. i have seen people force it too much only to find out that damaged something and had to get a new clutch. I find that installing the tailshaft in, with the car in gear that by rotating the tailshaft helps the splines mesh. Juggling the gearbox up and down and side to side does help but is very tiring. Once correctly in it is all just a matter of putting it all back together. Remember to put fresh oil in the gearbox- but make sure the plug at the bottom is in tight, and with new washer if required.
I have probably left something out, and when someone points it out I will probably feel like a goose, but it is up to you to take all the necessary safety precautions. This is what I did, but then I am not qualified as a mechanic so the responsibility is all yours, not mine. If you disagree with that, don't follow anything I have listed. Good luck and let us know how it goes