Solo. I haven't played D2 multiplayer.
Here's what I did. Ralla still had her rogue archer mercenary from Act I. She also had a couple points in Burst of Speed. We Bursted, then entered Duriel's lair and immediately set up a Town Portal (I have it hot-keyed to F1). Ralla had a few points in the first fire trap - can't remember the name - and she lobbed them at Duriel until the rogue got slaughtered. Then she'd TP back to town, resurrect the rogue, and repeat.
Hmmm, I guess I'll give that a try. I don't have any points in Burst of Speed, but I've got lots in the Fire Blast, and I think I have some magic items that increase speed anyway.
Do you have a high-speed connection, or are you dialing up?