I did a 6HDD swap on my VS a couple of years ago, pretty straight forward
going off memory:
* Get car up nice and high
* drop the exhaust, I took mine off from the extractors all the way to the tailpipe, the whole system came off (was just easiest that way as none of mine was flanged)
* Remove the torque converter inspection plate
* undo the trans cooler lines into the transmission
* drain the transmission (I removed the sump, drained it and put it back on, this relieves a lot of weight and stops a lot of mess)
* remove the entire tailshaft as one piece (from the transmission back to the diff) (you may also need to undo the handbrake cable to get this out)
* undo the torque converter to flexplate bolts by slowly rotating the engine from the harmonic balancer bolt (this is easiest with 2 people)
* undo the transmission bellhousing to engine bolts
* unclip and remove the large wiring harness plug from the top of the transmission, also disconnect the breather hose at the very top and the speed sensor plug
* slide trans back and drop out of car (this will be fkn heavy, be warned)
* whack the new one in (using the correct torque converter installation method, search the forums for this as I can't be bothered typing it out)
Repeat the process to put it all back together