I'm really excited, so I'm posting this, even though I'm still working:
I currently have ALS locked using the LSC system, and have (by hand, coarsely) found IR resonance! Hooray!
I looked at my error signals, as well as LSC-XARM_IN1 with dataviewer, and noticed that the XARM_IN1 signal was crazy when I was using the ALS signal as the error. I soon realized that this is because there was a non-zero element in the power normalization matrix, and I'm overriding the trigger. So, I was trying to divide by zero, and was getting crazy numbers. After zeroing the power normalization matrix element for the Xarm, the XARM_IN1 signal matched the ALSX_OUT, and I was easily able to acquire lock.
I had already re-transferred over the ALS versions of the filters, so that's what I'm using right now. Next up (on a 5 minute time-scale) is trying to acquire lock using the regular LSC filters.
Oh, also, something I hadn't thought of before dinner: I am setting the offset of the ALSX filter bank such that the output is centered around zero, so that I can lock, since these are not AC coupled servos.