Toyota and many other manufacturers have in fact given you control over the operation of the day time running lights. Many can be turned off by simply depressing the parking brake one click. This usually is not enough to cause any braking, or turn on any brake warning lights, but will de-activate the running lights. Give it a try.
BTW - The headlight switch, with it's built in circuit breaker, and the wiper switch, with it's delay wiper features, precludes a simple diode between the two to effect the desired solution being discussed. The wiper switch could never handle the extra current load of the headlights. The kit(s) that I've seen put each function under relay control and removes the heavy load from the switches.