The two files in the update rar — see aLoader-1.21ß-update.rar — are to be copied to the seplugins/aLoader directory, overwriting the original aloader_vsh.prx; aLoader.pbp remains as is (I think). If you experience problems with the beta, I suggest you revert back to version 1.20.
aLoader is compatible with Game Categories Light, which is a bonus. You should also take a look at “_aloader.conf” to adjust any configuration parameters if needed.
To install: Add the appropriate line to vsh.txt:
ms0:/seplugins/aLoader/aloader_vsh.prx 1