adjusting emergency brake cable and shoes
Just finished a 2005 today which should be the same.
There is no rubber plug but there is a metal disk the size of a quarter you can punch out. Looks like when you punch it out, it will fall inside the drum/rotor which will require you to remove the rotor to remove the piece. Then you have to find a suitably sized plug to fill the large hole it leaves in the backing plate.
Inside is a star wheel similar to what is found on the old style drum brake systems which you can rotate with a long flat blade screw driver.
If you recently replaced the rotors, you may find it easier to pull the rotor and adjust the start wheel with the rotor off. Tighten the adjuster to the shoes start to bind then back it off until the shoes completely clear the drum.
If the brakes have been on there for a while, you may find it impossible to pull the rotor off and you will NOT be able to adjust the brakes with the rotor off. To get the rotor off, you will have to punch in the disk so you can loosen the star wheel so the shoes will retract enough to pull the rotor. Remove the loose piece, reinstall the rotor and then adjust the start wheel with the rotor INSTALLED.
There is a procedure to take up slack in the cable. It involves an adjustment on the parking brake foot pedal assembly. The procedure for this can be viewed at AutoZone's website.
http://www.autozone.com/shopping/repairGuide.htm?pageId=0900c152801dc61e
emergency brake drum removal