First of all: a big thanks to the maker, this hack is epic
Instructions:
Download the hack
Open MW3
Make a custom class: take class 1 and pick 3 SUPPORT pointstreak rewards (example: uav, counter auv and sam turret)
Save that class and go to BARRACKS
ALT+Tab to leave MW3 and go to your desktop
Open the hack, select class 1 and select the killstreakrewards you want in the tabs
Hit save button and close hack
Go back to MW3
Check custom classes: class 1 should have the killstreaks you chose but with Support written next to it
Join a game and PWN the heck out of everyone
I hope this is clear enough?