The ECU is under the dash on the drivers side, next to all of your fuses. Check out Acks Faq or suzukiinfo.com, you can get FSM (Factory Service Manual's) that will show you how to tear most things apart.
Wrong vehicle. Samurai EFI ECMs are bolted to the passengers end of the firewall.
ghost, there is 1 screw holding the top of the ECM and 2 screws holding the bottom of the ECM. An impact driver is hard to use on the upper screw, since it is up high behind the dash. But sometimes you can use a impact driver, with a #3 bit, and with the impact driver handle being bigger than a normal screwdriver, it will give you enough leverage to be able to get the screw/bolt broke loose, so you can remove it. If you can't get it out that way, and you don't want to remove the dash, then if you remove the battery, you can see the end of the top bolt on the engine compartment side of the firewall. You can take a torch and heat up the bolt and that should make the bolt much easier to remove by hand. A torch will damage the paint a little bit, but not usually too bad, and a little touch up paint will take care of it.
Also, EFI samurais do have a diagnostic slot in the fuse block (the lower right hand slot). You can put a fuse in that slot, turn the key to run and the CEL should start flashing, to tell you what codes the ECM has in it.
The ECM is very likely the issue with the coil having no fire. EFI samurais have well known problems with the capacitors in the ECM going bad and needing replaced, as well as needing some of the traces on the board fixed (because of the caps leaking and damaging them).