[Zero10]

With the alternating DC trick, make sure you only connect the wires for a VERY short time. A trick a lot of people do is to use a 9V battery not a 12V battery, this helps because.......

Fuel injectors are solenoids. When you first apply power that energy goes into producing a magnetic field, that magnetic field is doing work, and while the magnetic flux is changing it produces a counter-EMF in the coil wire inside the injector. This counter-EMF serves to reduce the overall current flow through the injector coil. This means, for the first split second the injector is connected it draws only a small amount of current.
Once the needle / solenoid component comes to a rest (the click you hear) the magnetic flux is no longer changing and the current draw increases DRASTICALLY, since it is now simply a resistor and not an inductor. If you leave +12V connected for this time period the wiring will heat up to the point of melting the insulation in a very short time (varies by injector, but it can be as short as 1/2 second), then the injector will develop an internal short and no longer function properly.

By using a 9V supply you increase the margin of time you have by reducing the rate at which the wiring heats up.

This is why injector cleaners use a very high frequency short duration pulsed power supply.

*EDIT*
Oh yeah, nobody will knock you for working on a 300ZX, as long as every time you get in your Porsche you apologize to it.