There is no real way to cheat either of the armor abilities, but then again, the requirements to actually increase the skill is as basic as it gets. Take damage while wearing armor of either type to increase your skill in either armor type. You can combine this with the grinding of restoration magic in order to kill 2 birds. You are going to take damage for the entire game though, so this shouldn’t be much trouble to anyone.
If you are really needing to increase this, find the weakest enemy you can find and make it hostile toward you. Stand around and let them beat the crap out of you. Since they are a low level, weak enemy, they should do very little damage to you, but your armor skills will increase. You can use restoration magic spells to make sure your health stays high and you don’t accidentally get killed.