Since you put back in the amount that you drained, did it match what the factory calls for (i.e., say, you drained 3.7L and the manual says that the capacity is 4L. The 3.7L, in this generic example, would be close enough, including some residual that remains above the drain hole.)
The easiest thing to do, is what Tegger mentions, since it's idiot-proof. You fill through the fill hole until it dribbles out. There is no need to measure what comes out to figure out how much to put back in; there is no dipstick to interpret; there is no guessing. Just make sure you're level.
What I did on my STI once, when a lift wasn't available in the hobby shop, was lift the car on the driver-side, so that when I added the transmission lube it filled away from the hole. When I put in the amount that I expected to use, I did the following:
1. Lower the car so that it is on flat ground.
2. Check to see if any gear lube is dribbling out.
3. If oil dribbles out, you're done. If oil does not dribble out, continue to step 4
4. Raise the car again from the driver-side and add a couple of hundred mL more.
5. Repeat steps 1 through 4 until finished.
