Just run T's in each line. Unplug the feed line to fuel, and if you are concerned about the environment, hook an overflow tank (I use an old Hayes two ouncer, from the days when I used header tanks on helicopters) to the vent line during the process.

Due to the YS design, no fuel can enter the engine unless the crankshaft is turning. So, no worries about flooding it out during fueling.

Steve