you can do it without dropping the subframe, but its fiddly.
remove the wheel, stalk trim and stalks, then undo the bolt holding the lock housing to the outer column tube, this is usually a shear bolt on a mk3, but luckily its usually fingertight so not hard to undo. next remove the undertray in the drivers footwell, then undo and remove the bolt holding the uj to the bottom of the column, dont loose the spring. yank the column out of the car, and set aside. make sure you disconnected all the electrical bits, not sure how the airbag hooks up to the column but it should be self evident. if not, you only need to pull it up enough to release it from the UJ really.
now go into the engine bay, if you look thru the boot hole there is a bolt which holds the UJ to the rack, remove this and pull the uj inside the car to release it. now remove the rest of the boot and fit the new one, refitting is the reverse of removal as they say.
oh and for the ign lock shear bolt replace it with a suitable allen bolt, or just tighten it up as best you can with mole grips. doesnt have to be mega tight just enough to stop everything wiggling about