There's actually quite a small number. At three moves, it's one of the stats with the lowest amount of moves that boost it.
- Acupressure, which increases a random stat; including accuracy.
- Hone Claws, as you mentioned. As well as accuracy, it also boosts Attack.
- Coil being the last one, which also increases Attack and Defence.
Excadrill can only learn one of the moves, which is Hone Claws.
http://bulbapedia.bulbagarden.net/wiki/Accuracy
Also, if this is intended to boost the accuracy of Excadrill's Guillotine, the formula works a bit differently. Accuracy boosts are not taken into account.
Accuracy = ((User's level - Target's level) + 30)%
http://bulbapedia.bulbagarden.net/wiki/One-hit_knockout_move