I had to do the exact same task to get an oil sample with the Cat kit. They provide a very small plastic tube that fits down the dipstick tube. I used the Mityvac to lift the oil just up to the pump, pinched the hose, removed the Mityvac, placed the collection bottle on the ground (4 inches below the bottom of the pan) and waited. And waited. And waited. And waited. It literally took two hours to collect the three ounces in the collection bottle.

Cold oil flows very slowly especially with only a 4 inch head pressure.