First off, I've never re-wired a guitar before, and lately I've been eyeballing this Seymour Duncan Black Winter on Reverb, and wondering if I could just drop that into my active HSS LTD without any problems. I haven't been able to find an HSS wiring diagram anywhere, let alone one for active pickups.

P.S. I'm not sure if just the humbucker is active or both the single coils are as well, and I have no idea how to find out. All 3 pickups are blackout-style "ESP Designed" pickups, and the guitar is an ESP MH 103QM with a rosewood fingerboard if it helps.
Just out of curiosity, what makes you think the guitar has active pickups? The MH 103QM comes with passive pickups from the factory; they might be plastic-covered ones, but there's no battery and they're still passive. Most people tend to run pickups as either all passive or all active, for the sake of simplicity.

Anyway, I'm 99% sure that your pickups are passive (if they're the stock set), so you can just swap a Black Winter straight in.

PS. Most people use these diagrams: http://www.seymourduncan.com/wiring-diagrams
Quote by tubbyanos
I know its active because there's a battery, which has been changed once or twice due to the pickups sounding weak.https://postimg.org/image/ifpg81q2f/ that's how they look.

Ah, gotcha. They must have been making those a few years back.

If' you're dead set on the Black Winter, you're best off either ditching the single coils altogether, or buying a pair of cheap ones to drop in (together with replacement pots at 500k or 250k, a 0.047µf capacitor, and a bridge grounding wire). This is worth a read: http://www.seymourduncan.com/blog/the-tone-garage/active-and-passive-in-the-same-guitar-can-it-be-done.
You can't just drop a passive pickup in an active circuit. First find out of those are passive pickups with an active preamp. If they are, then it might work. If they are truly active, you either should switch to a true active pickup or switch the entire circuit to passive (new pots, no battery, etc). It is possible to mix active & passive, but I don't recommend it.
Dave @ Seymour Duncan
Thanks for the replies! I'll probably buy an active pickup instead, or just leave it as-is. I only wanted the Black Winter after finding a nice looking one cheap on reverb and liking a few of the sound demos I heard when I looked it up. Now that I know how much trouble it would be to put it in my ESP (either change all electronics besides the jack or struggle to have it co-exist with the active single coils I never use anyways) it just seems like the more logical choice. Thanks again for all the help here. This whole "swapping pickups in guitars" thing is pretty new to me, so needless to say this has been a big learning experience regardless of the outcome.

P.S. I like your profile picture mintsauce