The battery is very easy to get to. The only issue is that once you've been in there it's tough to get all the plastic pieces back into their proper positions. There is one corner of the cover that insists on sticking up a bit.
I connected mine directly to the battery along with my GPS unit. I've done it this way on all my previous bikes except the Trophy which had BMW jacks from the factory. All touring bikes should have a pair of these jacks.
How many amps does the controller need for the jacket?
My Gerbing gloves only uses about 1.5 amps max to supply the variable controller. I had to look it up on the Gerbing website (or maybe I did email them, don't remember since it was a long while ago).
I like to keep the connections on the battery posts to a minimum so I like having one larger wire supply a Aux fuse panel for stuff I add... usually. On the CTX there are a few plugs that are wired for options that are not standard in the U.S.A. versions. I don't intend to install the very pricy Honda options for some of these connectors so will use those for other things as I am able. One is the front option plug next to the ignition switch under the top shelter which includes ACC and ground pins with the 10 amp fuse provided in the fuse box. This plug, like any other option plug not yet used, has a dummy cap/plug to seal it from weather that is really just a regular connector with seals where the wires would normally come out. Pins are available for these through a few sources. I bought pins for the front option connector and also pins for the 12v socket connector under the seat (different sized pins), and the seals that go with 18ga wire (what I used) and populated these plugs for my own purpose.
If I need to add anything else to direct connect to the battery I will simply use the connection through an inline fuse I already have there (12ga wire with 15amp fuse currently improving power to the horns and alternately to a dedicated 15amp 12v socket for emergencies I added (I have 2 sockets)).