First, you can't get that pan off w/o lowering the subframe and besides, unless the chemical gasket's leaking (rare), you won't see ANYTHING in there. All that's there is the valve body and soleniods, NO filter or anything serviceable.
You properly flush the trans by removing the upper trans cooler line as described at Bay13
http://www.volvospeed.com/bay13.htm, look under trans.
There's no need to even remove the trans drain plug on the bottom but it takes about 12 qts of new fluid pumped through it until you see new red fluid come out. Do it by doing 4 4 qt fluid flushes, put 4 qts in each time after seeing the air bubbles in the clear plastic hose. When you're seeing red fluid after about 12 qts have gone through, put the cooler line back on (being sure clip is secured) and finally add about 3 qts, check level.
Don't waste time and money with filters and magnets, the fluid flush is all that's needed.