The stock quadrant is self adjusting, grab the pedal and yank UP on it and it should take up any slack in the cable. You'll hear a ratcheting noise as it self adjusts. Beyond that there really isn't anything else you can do. If the clutch is slipping there isn't much you can do but replace the clutch.
2000 Mustang GT Steeda #0048
Just because I give you advice, doesn't mean I know more than you. Its just means I've done more stupid ****.