Well, I installed the boost gauge. Unfortunately I loaned my camera to a Lancer owner because he was swapping a blown stock motor for a working stock motor and wanted to document it. Here's the low down on the installs, and F means female and M means male:
Boost Gauge
1. Go to Home Depot and buy a combination of brass fittings that will give you a 3/16 barb at the end. I ended up doing this: 1/8NPT M on the end of the gauge -> 1/8NPT F to 1/4NPT M, 1/4NPT F to 1/4NPT F, 1/4NPT M to 3/16 barb. It sounds like a lot of fittings, and it is, but I couldn't find a 1/8NPT F to 3/16 barb at any local hardware store.
2. Get 6' of 5/32 or 3/16 vacuum hose. I got 5/32 just because that's all they had.
3. Get a 3/16 tee fitting
4. Get about 3' of 18 gauge wire (I used some speaker wire, just because I had it and it was easier to work with) and some 22-18 gauge wire taps (the red ones)
5. Run the vac line, instructions can be found by searching, but just poke a hole in the grommet where the amp power cable goes and you're good to go. Tap into a vac line on the intake manifold, I used the small U shaped vac line, works just fine.
6. Connect the light bulb. Pop out the dimmer switch from behind the dash. Tap the 18 gauge wire from the light bulb onto the two wires on the dimmer that ARE NOT BLACK. It doesn't matter which wires from the bulb go to which one on the dimmer because they will complete the circuit at the bulb no matter which way you do it.
7. Mount the gauge and you're done. It took me about 30 minutes.
Air/Fuel Ratio Gauge
I didn't install this, but it's pretty easy. Mine came with three wires coming out the back (red, black, and some other color). Tap the red wire into an accessory wire. I'm going to tap into my turbo timer ACC wire for this and future accessory installs. Black wire goes to a good ground (tapping into TT ground). The "other" wire taps into the O2 sensor signal wire. Since I didn't have to pull things apart this weekend to install anything else, I didn't look for the O2 sensor wires. There should be a grommet with wires coming through somewhere under or next to the center console. Tap into the wire that's the signal wire. This could also be done at the ECU, it's pin 35. I'm going to tap wherever it's most convenient for my to mount my WBO2, since that has narrowband output.
Turbo Timer
How you run your wires will depend on where you mount the turbo timer. I have a Greddy, and I mounted mine in the little cubby under the dimmer switch. I drilled a big hole in the back to run the wires. The Greddy wires are about 16-14 gauge, but the ignition wires are 12 gauge, so using wire taps will not work in my case. I had to solder and tape, which wasn't that big of a deal.
1. Run a search on "timer + install" and look through the threads for some good information and pictures.
2. Take off the plastic panels under the steering column. One is held on by three screws, the other by two clips on the top and swivel clips on the bottom. Pretty easy to remove.
3. Pull the stock ignition harness off. It's about 8 inches in length, has two bright red wires, two blue wires, a black and white wire, and a black and orange wire. Just disconnect the plugs and pull it towards you. It won't come out because of some other wiring, but you don't need it out any ways.
4. Use a wire tool to pull back the red wire sheath. I cut into it, pushed it back, then used a knife to slit open the wire sheath some more to expose it. Wrap the 12V line of the TT (Greddy's is red) onto this, solder, and tape.
5. Use a wire tool to pull back the sheath on the black and white wire. Use the same technique above to expose more wire. Wrap the Accessory wire from the TT (Greddy's is blue) around this, solder, tape.
6. Do the same wire technique as above to the blue wire IN THE MIDDLE of the harness. There is another blue wire in the corner of the harness, leave that one alone. The blue one to tap into is right below the black and white one. Wrap the ignition wire from the TT (Greddy's is green) around this, solder, and tape.
7. Gound the TT. I found a nut under the dash, put a claw wire end on the ground wire, and put it on the nut. Formed a perfect ground.
8. Test out the TT. I turned the ignition to "On" (did not start it) and the TT came to life. Turned the ignition to "Off", and the TT kept the car on for 30 seconds. All done. This took about an hour, because I was taking my time, drinking beer, and working with the A-pillar all at the same time.