I did a posting on my experience replacing the cells on my 1989 560SEL. Do a search by my username.
I agree it could be easy to cross thread, especially if you are laying on your back in the driveway, not on a lift. Also, ensure you have metric line wrenches, as it is easy to strip off the fittings. Have fun!!
1989 560SEL (172k)
1989 325IC (122K)
2004 Suzuki Volusia LE (3500 miles)
2005 Yamaha Road Star (20 K miles)