Tons of companies make lock-on grips that use allen bolts to secure the grip to the bar; any local or online bike shop will carry them. They work great, but because they have a stiff inner core, I don't find them to be as comfortable as non-locking grips.
With proper installation, non-locking grips shouldn't twist. Swish some rubbing alcohol inside the grip, and slip them onto your bars. Once on, you can shoot some compressed air between the grip and the bar or use a hair dryer to accelerate the evaporation. Otherwise, wait a day and they should be solid.
I'm using ESI silicone grips these days, and using the method just described, they
really stay on the bars, to the point where it's a bit of a pain to take them off!
Hope this helps!