Here's a mediocre sketch for anyone who doesn't have access to binary groups....

Viewed sketch with courier or other fixed font:

A = Cable from pole to be fastened here on house
AB = Cable to run under eaves, fastened to inside of fascia board
B = Cable interconnection box high under eaves. New hole for cable near box to enter through garage and run along wall near ceiling
C = Cable to drop down and enter office thru new hole in garage/office wall
o = New cable
= : Wall
| : Wall
.. : Empty space

==================================
|................|...............|
|...GARAGE.......|.....OFFICE....|
|...............C|...............|
|..............oo|oo.PC..........|
|..............o.|...............|
|..............o.|...............|
|..............o.|================
|..............o.|...............|
|..............o.|...............|
|..............o.|...............|
|..............o.|....ROOM.......|
|..............o.|...............|
|..............o.|...............|
|..............o.|================
|..............o.|B..............A
|..............o-|oooooooooooooooo
|................|
==================

..............OUTSIDE..............