Heres a picture of the T-fitting used to hook up the boost guage.

That wasnt very hard to do, just pull the vacuum tube off, cut a little section out and put the T-fitting on.

The hardest part of install the boost guage is running the vacuum tube through the firewall to the boost guage.
It took me a while to get a hole in the little plug right the break peddle in the inside of the car.
The picture below is of it from the engine bay.
I used a pen to keep the hole open and just left the casing of the pen there to run the vaccum line through.