Just have the keypress trigger a boolean to change and use that same variable in a loop to determine to modify the memory.
//At top of program
BOOL sBullets = false;
//top of main loop
sBullets = !sBullets //Switch state to opposite
//In loop farther down
memcpy((LPVOID)SuperBullets, "\x33\xC0\x90", 3);//ON
memcpy((LPVOID)SuperBullets, "\x0F\x94\xC0", 3);//OFF