Unfortunately, you can't learn anything past what you purchase from your skill trainer. However you can RE the Modification Mods from the Blackhole & Campaign Gear, but not the Armoring. Why this is, I have no freaking clue, Cybertech is full of fail imp. I have it and am very disappointed in the lackluster of what you can RE compared to many other professions.
armor mod schematics and mod schematics drop off of random trash mobs in EV and KP normal mode.
actually had one drop for me the other day when we decided to goof off with an alt raid in EV.
link to keen mod 24: