You can install the switch backs to make sure they light up without the resistors.
The resistors are used to solve a signal light flashing problem, called hyper flash. The resistor is connected between the positive lead to the signal light and ground. It will produce a fair amount of heat so clamping or taping it to the plastic of the light housing is not a good idea. Clamp it to metal is much better. It is creating the same amount of current draw as a regular filament bulb does.
The flasher unit will flash rapidly if one of your filament bulbs is blown, because the current draw is much less than it should be. With LED lights,the current draw is typically 1/10th of a filament bulb, so the flasher unit will indicate you have a burnt out bulb.
A better method, but more technically challenging is to modify the sensing resistor in the flasher circuit. If you have a 2005-2011 truck, check out this thread.
RE: switchback problems:
some folks are having problems with the switch backs because they are designed to take advantage of a hi, and low circuit of a 3157 bulb wiring.
the normal bulb has two filaments in it, one that lights up 5x brighter than the other. The front DRL//signal light on the Tacoma only has two wires, a ground, and the wire to light up the high circuit. It is also a CK socket that is wired differently than the rear brakes/ signals that use the regular 3157/3156 socket.
Some switchbacks are expecting the white LEDs to operate from the low circuit, and the amber LEDs to operate from the hi circuit. Since there is only one wire to your front signals, so only one part of the switch back works. That is one of the reasons some LED distributors let you know that they won't work on DRL sockets.