Under your airbox, you'll see the PMV assembly. 2 brake lines coming in to it on the end, and 4 coming out. Big black thing, with a cylindrical object on top. The easiest way that I can think of is to disconnect the connector on the auxiliary fluid reservior. That will make the EBCM think the fluid is low, and fault out the traction. If this works, you could actually put a switch in if you wanted, but it will throw a traction warning light on the dash while disconnected.
This SHOULDN'T mes with the ABS, as the reservior is only used to pressurize a small amount of fluid behind the modulator valves to be used for traction. ABS doesn't use this reservior.
You can also follow the brake fluid from the main reservior to the PMV. It'* a larger black rubber line.