If Eric's technique doesn't work, you can add a break or a loop of extra webbing on one side. Once you have one arm out, the other is easy. Here's a couple of pictures from an earlier thread where we discussed this: Subgravity Paragon harness
Sub-Gravity's Paragon style quick release/adjustable buckles can be purchased directly from Sub-G or slightly less expensive from piranhadivemfg.com.
-Z