No problem at all using jacks, just do one end at a time. Make sure you loosen the nuts before lifting the gbox or engine. You can jack under the gbox without issue, use wood under the sump. You may need to tip the engine from side to side, I can't remember.
Wood and trolley jack under sump. The drivers engine mount on the chassis can be removed by cutting one of the bolts. But you can't put one back. Unless you manage to move the engine.
Engine mounts can be a pig due to limited access. You need to unbolt the underneath and then grip the rubber mount and twist to remove the threaded part. The metal engine mount on the chassis will get in the way also.