its actually quite an easy job.
remove most of the things on top of the gearbox to access the bolts, remove the starter-motor. under the car you need to remove the drive-shafts, empty the gearbox oil before you pop them out
and then just remove some bars here and there, and if i remember correct one of the engine mounts. just put a "jack"(don't know the english word, lift?) under the engine to be able to raise and lower it as needed.
but if your brother is familiar with cars, he would know what to do next
also, there are rover 620ti's workshop manuals laying around on the forums. rovertech.net is one of them..