Hate to keep plugging the book from Pelican, but they have a great writeup about removing/reinstalling hollow camshafts. The one they use is for the M50, but the theory is the same.
First, find the "sweet spot" where the only lobes pushing down on the lifters is for cyl 1. If you get those lobes facing straight down, most likely the cam will stay put, but I held the square end with a crescent wrench to keep it from turning the entire time.
Once those lobes are down, you will see that lobes for the other three cyl's are not under any kind of pressure. At this point you can remove all of the nuts on the carriers EXCEPT the one straddling the 1 Cyl.
After you get all of those off, CAREFULLY remove the last two nuts one quarter turn at a time. You will see that the nuts have hash marks on the top, just line them up horizontally or vertically, then turn one quarter turn, turn the other one quarter turn and repeat. It's a slow process and they will not release until they reach the very tippy top of the stud. (Try not to let them go flying across the room when they finally come off the thread)
To reinstall, reverse the process. I relieved the hydraulic pressure from the lifters on cyl. 1 and I was able to get the nuts started on the studs. Again, turn them one quarter turn until snug. Make sure you or your partner have a good grip on the camshaft, as you don't want it to turn at all. Once those are snug, you should be able to reinstall all of the other caps and torque in a logical order.
The caps are numbered, so make sure they go back onto the correct studs when reinstalling.
The book goes into a lot more detail, I highly recommend it.
Good Luck!