FYI for anyone interested, I got the forearms to work by adding one extra step in Poser 5 itself. Previously before conforming the suit to Vicky 3 I had gone into the Poser 5 Joint Parameters and zeroed Vicky's pose. What I hadn't done was click the align button. When I did this it reset the X alignment, and now the sleeves remain in place for the most part. There still remains a slight flair around the cuffs in certain poses, but other poses like the original one in this thread work.