Lea Rogers of Ramjet Productions wrote in to let us know about his Disco House Funk Guitar Loops, a free collection of guitar loops.
I created these a few years ago, and they fit well into the above genres. Most sequencers will do timestretch or warp marking to adjust tempo.
Each zip file contains between 13-37 individual 44khz 16 bit WAV 120 bpm loops with various guitar effects (phaser/delay/wah/talk box).
The guitar loops come in download packs with various keys.
More information: Ramjet Productions