I hope I got it sorted out. Here's what I ended up with if anyone's interested:
I bought an AimSHOT TX75 Xenon Illuminator light, which has an on/off/momentary switch at the rear, 3.25 oz., 4.9 in. length, 1.12 in diameter, a very intense 120 lumens. $55 + shipping @Azeotek.
I also ordered AimSHOT's universal rail light & green laser mount (elongated Weaver style 1" mount, $10) and a on/off pressure switch with 8" cord ($11). Didn't end up needing or using either.
Then I ordered Hi Point's compensator and accessory rail ($20 from Hi Point, incl. shipping), which I was told would fit accessories from 3/4" to 1" in diameter. It didn't - it's strictly for 3/4" accessories like a red laser. I mounted the accessory rail below the barrel, although I suppose it could be mounted to one side or the other since the compensator just slides over the barrel and is held/pinched in place by a single screw.
However the compensator's point of attachment for the mount turned out to be a standard 3/8" 22 style dovetail and I couldn't use the Weeaver style mount. I had a selection of 1" rimfire rings to choose from. I tried a Simmons and Tasco, both of which worked, but then found an old set of Tasco see-through mounts. This ring was slightly wider than the other 2 and of course is forward end of the compensator and the rear (where the on/off switch is located) is just slightly below the bottom of the forend. There's room to remove the cap and batteries without taking the light or mount off the gun.
Because the Hi Point carbine is so short, I've no need of the on/off pressure switch. It's very comfortable to just push the light's momentary on/off button with my left forefinger when I'm holding the rifle.
So I've got a low tech weapon light mounted for the cost of the light, the compensator, and whatever one half of a 20 year old set of Tasco see-through rimfire rings cost me. And I ended up with some spare parts that'll no doubt find a home on something else, somewhere and some time: the AimSHOT universal Weaver sytyle mount wouldn't work with the Hi Point compensator (wish they'd told me at Hi Point that the accessory thingy mounted to the compensator via a standard dovetail!), the pressure switch for an aimshot light that I'll keep it in case I put that light or another on something else, a Hi Point accessory mount, and one 3/8" dovetail 1" ring.
I haven't shot it since the add-ons so I don't know if it'll shoot to the same POI or whether accuracy has changed. I bet it'll work just fine for home protection and shots <40 yards. I can post a photo or two (maybe) if anyone's interested. -WSJ