I read some of the installation proedures others have posted and stole some info from the AWE center vent gauge installation guide.
The steps documented below were born from the fact I could not remove the windshield wiper arm in order to gain access to the ECU area. I tried and decided I didn't want to damage the wiper arm or anything else trying remove it.
Anyhow here is what I think is the easiest way to run the vacuum lines for a boost gauge.
After removing the knee bolster and looking for a grommet to pass the line through I found a big grommet that has 7 openings on it and 2 of them are already used.
After jacking the driver side of the car up and removing the wheel I found the other side of this grommet
If you look on the other side of the wheel well there is another grommet that accesses right into the engine bay and directly under the intake manifold where the boost line you want to tap into hangs.
I chose the 3rd nipple on the bottom row as it was the closest to the size of my vacuum tube. I snipped the tip of it off and also made a small slit on the top to allow for the tapered end of the nipple to expand if needed to accomodate the tub as I fed it through from the inside
Fed it past any cables and into the engine bay
I secured the vacuum tubing to the existing lines so there is no way it was going to move around and trimmed it up