Well, I installed the belt today. First I removed 3 bolts (3/8″) that hold down everything (last picture).
Then removed 4 bolts (3/8″) from the pump thing. This is how you get the belt on.
Then put the belt around the plunger then around the small gear. Then roll it around the large gear. Done!
Misc. information about the compressor:
To order the belt just call 1-888-895-4549 and ask for the 007-0068 belt. It is the only belt they ship / sell, so it is easy.
Kobalt (aka Lowes 99007 vlk1582609) 26 gallon air compressor manual: http://www.powermate.com/productmanuals.php