Can you share a little more about what is going on (wrong) with the ABS in your truck? I know the system may not be the nicest one out there, but it should work. Can you tell us about the truck, how it differs from stock and what you are experiencing?
It is unnecessary for the OP to post more details. It is extremely common to see these complaints this time of year because of SNOW and ICE. ABS freaks out on these surfaces creating dangerous situations where the driver is unable to stop the vehicle. Creating a way for the vehicle operator to disable the ABS system would seemingly precipitate us into a seething cauldron of debate. But debate is not necessary. The ABS system eliminates the need for the driver to learn and understand threshold braking procedures. And it is undisputed that ABS is a system where you trade an increased distance required to stop, for steering control. The bottom line is ABS is fine for dry and sometimes wet pavement conditions. When off-road where there is loose sand, gravel on steep terrain, or onroad where there is SNOW or ICE the ABS system is
downright dangerous. In these conditions it creates a supremely dangerous set of circumstances where no matter what, the driver can't stop the vehicle. Also many people erroneously belive that it's federally required for vehiclels to be sold to be equiped with ABS. This of course is a myth. VSC (ESC), is federally required but not ABS.
There is nothing wrong with a driver disabling ABS on the road or off-road, as long as they understand what they are doing and how it affects the operation of their vechile.
As for the '06 4runner, I'm sure pulling a fuse is the easiest way. Consult the documentation for the fuse/relay block. I know several tacoma owners would do this that did not have a kill switch installed and it worked great for them.