picking the relay i need

I forgot to mention that you will need to run the output of the above setup to a fifth relay to give you the result you are looking for. 12 V + output to 86 of the fifth relay.  Ground 85.  30 goes to the wire that has ground when you push trunk release button.    87A to one wire and 87 to the other wire.  The state of the fifth relay will determine which of the 2 wires will see the ground that is going to be on 30.

As Kevin stated, in an energized state, a relay will draw about 160 milliamps each.  One relay staying engaged can run a battery down in a day or so.  4 or 5 of them, will be worse.

so true. not only that, think of the cost involved with that many relays as well as the size. the 0047 electronic relay would be cheaper, or you could build your own electronic solution for less and the space and size would be worth it by far.

I would do it with either a microcontroller or a flip flop.  Unfortunately both are going to require a bit of circuity.

The microcontroller is nice because you don't need any calculations or debounce circuitry - you can use general interface circuits and do all the timing in the software.  The drawback here is most microcontrollers are 5vdc so you'll need a power supply circuit.

A flip flop can generally be ran at 12vdc so you won't need a power supply, but you'll need to build a debounce interface that may require you to make some calculations and test some things out to make sure you get rid of all the bounce.

Both solutions will leave you with "memory" that doesn't involve latching a relay so your standby current will be extremely low.

Another item you can use is the TR-7 module - it does exactly what you want it to do.  You give it a single pulsed ground and it will provide either constant power or ground (depending on which wire you use.)  Give it the same pulsed ground (you can also give a pulsed positive signal) and it will turn the output off.  I use the TR-7 to bypass the ECU on my Stratus to power the fog lights with the factory momentary switch independent of the headlights or highbeams.

Search for "PAC TR-7" on google and you'll find it easily.  It's kinda pricey - over $30, shipped.  But it does 7 different functions, is programmable, and can be reprogrammed for other uses.

Jeff