| Move it to the GAME folder. eg. Removable Disc>PSP>Game.
If you have a folder called 'GAME340' or anything like that, as long as it's NOT called 'GAME150', put it in there.
If not, just put it in GAME, and in recovery mode (you can get there by turning the PSP off completely, and holding the right shoulder when you turn it back on), look around for the option that changes the Kernel to...whatever the highest one is. Anything that isn't 1.50.
Hard to do without knowing what firmware you have. If it's not Custom Firmware it won't work. | 
Linear Mode
