Seeing as alot of people have been having trouble with installing this, i decided to make my first contribution to the forums.
To install the 1.50 Kernel add-on follow these simple steps:
1. First upgrade to 3.80 M33/M33-2. (If you havn't follow this guide first)
2. Download the 1.50 Kernel add-on from HERE and save it to somewhere convient.
3. Extract the 1.50 add-on to a folder named UPDATE.
4. Copy the UPDATE folder to X:/PSP/GAME380/
5. Next Download the 1.50 EBOOT from HERE
6. Extract the contents of the Zip folder to the root of the memory stick, eg. F:/, and rename the eboot to 150.PBP
7. Make sure you disable the USB connection correctly then go to GAME on the PSP and the 1.50 Kernel Add-On should appear.
Hope this works!!