You're right, there isn't any room in there to get to anything once
the engine is in the bay. Attach the cable to the engine with a EZ
connector before mounting the engine. Then as you lower the
engine into the bay, slide the cable in through the hole in the fire-
wall into the nylon sleeve. You have to work the engine in care-
fully while sliding the cable in. Leave the cable full length at first,
until the engine is mounted. Then you can adjust the throttle at
the servo with another EZ connector on the servo arm. Once you
get the whole deal where you want it, and the throttle does what
it's supposed to do, then you can cut the cable on the servo end.
I used a pair of wire side-cutters on the cable and then soldered
the cut end to keep it from fraying. It doesn't fray when you first
cut it as the snips crush the ends together. I also locktite the hold
down screws on the EZ connectors. Here's a pic:

Jesse