I keep a 4" length of fuel tubing. Squirt the oil in the tube (I carry mine in a squeeze bottle with a tip that fits the tubing - and use Dextron III ATF), attach the tube to the intake barb. Cover the exhaust with my finger (optional) and spin the prop a few times. It sucks the oil out of the tube.

If you have a cowl so tight you can't get forceps in to access the carb fitting - pull the glow plug.