I followed the manual to the 'T' but still failed to get this to work.

Has anyone had any luck adjusting the parking brake after installing new rotors/pads?

 

Failed to get what to work exactly? Don't know the exact instructions for your car but in general I adjust the star wheel until the rotor locks then back it off 4-6 clicks.

 

1. Release the parking brake, loosen the locking nut.
2. Remove the rear wheels, line up the hole in the rotor with the star wheel, move those with a flat head.
3. Hold the adjustment nut on the brake pedal with a wrench, tighten the locking nut.

I followed all of this and the parking brake pedal still goes all the way to the floor.

 

Maybe a cable has been disconnected from one of the levers on the backing plate?

 

I have never adjusted the cable at the pedal. Ever. You need to adjust the star wheel until the disc locks up, then back off 3 clicks. This is done with the brake completely off. Once you've done this, it should only take 30 - 40% of the pedal travel to hold the car even on a steep slope.

 

I haven't had to adjust the pedal either on my isf when I did pads and rotors, just on the h/b shoes adjustment themselves. Lockup then back off till it can spin, job done. . But in saying this I just did pads rotors on a Is250 last week and locked up and backed off and the travel was terrible or as bad as it was prior. So removed the kick under panel to get to the handbrake cable adjustment. Removed the locknut and adjusted it there with the wheels off the ground. Just to make sure it wasn't starting to bind at all. Didn't take much and now about 3 clicks.