how do i install a firewall adjuster.

Take the cable loose from the quadrant undr the dash. Pull it out through the engine bay. Remove the rubber retaining washer from the cable. Install your new firewall adjuster in the hole in the firewall. Adjust it all the way in. Put your cable back through and re-hook it to the quadrant undr the dash. Adjust the forewall adjuster out to your liking. Drink a beverage.
 
Unhook your cable from your quadrant from under your dash.
Unbolt your cable from the firewall, there should be one screw holding it on.
Pull your cable out of your firewall.
Get a file and file off the little stubs holding the black, rubber bushing on the end of your cable.
Pull it off and slide your adjuster on the cable.
Fish the cable back into the firewall and bolt it back on.
Hook your cable back onto your quadrant under your dash.
Now adjust to your needs.

I hope I didn't leave anything out! Good luck.