primative, check out this thread:
http://www.c-brats.com/viewtopic.php?t=17114
The process described there is similar to what you would need to do, and it also includes some cross section drawings that should help you visualize. Note that the cross sections were for smaller transom penetrations that don't go all the way through, but in your case you do have access from both sides, and your holes will be quite a bit bigger.
Here's one of the images:
The lighter yellow is the transom core and the darker orange/yellow is the epoxy "plug".
http://www.c-brats.com/viewtopic.php?t=17114
The process described there is similar to what you would need to do, and it also includes some cross section drawings that should help you visualize. Note that the cross sections were for smaller transom penetrations that don't go all the way through, but in your case you do have access from both sides, and your holes will be quite a bit bigger.
Here's one of the images:

The lighter yellow is the transom core and the darker orange/yellow is the epoxy "plug".