Please post up any tips and photos of removing the bumpers and installing the tow hooks. The instructions don't have a lot of detail to them so photos will be helpful.
While not the exact same procedure these Roush instructions should help if not cover everything you'll need to know.
Front Bumper Removal:
www.roushperformance.com/parts/manuals/Mustang-Front-Fascia-with-Foglamps-and-Harness-2010-2012-1310R17C381IM-AA.pdf
Rear Valance Removal:
www.roushperformance.com/parts/manuals/Rear-Valance-for-Mustang-GT-2010-2012-420009-manual.pdf
While not the exact same procedure these Roush instructions should help if not cover everything you'll need to know.
Front Bumper Removal:
www.roushperformance.com/parts/manuals/Mustang-Front-Fascia-with-Foglamps-and-Harness-2010-2012-1310R17C381IM-AA.pdf
Rear Valance Removal:
www.roushperformance.com/parts/manuals/Rear-Valance-for-Mustang-GT-2010-2012-420009-manual.pdf