I'm installing gauges right now and I want to use the power from the clock, except I can't see which is the constant power on the schematic. I could whip out the multimeter but I can't find it anywhere. I could also touch the wires to the ground but that's definitely a bad idea. I could also take a guess and try it but I don't feel like doing it twice if it doesn't work.

Here's a link to the schematic:

http://www.whatanight.net/7-WIRING-clock.pdf

So YG is accessory, B is ground (obviously), but are the other 2 constant or is only one constant and the other one something else?

Also, is there a way to connect the wires to the original connector or do I really need to cut the connector and strip the wires? I'd prefer keeping the connector if I ever have to reconnect the clock for some odd reason.

The blue/red wire tied to fuse #2 is the hot lead at all times to the clock. Just tap into the wire and don't cut off the connector.