Like RA1N said thats the only way
The slims CPU's are different than the fats and can only run 3.60+
But...Dark-Alex made a homebrew app that will take the 1.50, 3.40, and the 3.60psar(Which is illegal to give to others) and make a bootable firmware thats on the memory stick all you need are those files and a Pandoras Battery.