The installer mounts dev_flash as in FREEFLASH and Alijandro, so it itself can write to dev_flash. After running the installer enter a file manager proceed to copy over whatever you want. One tutorial this guy permanently changed his fonts, I myself edited a couple .rco files to change my app_home/PS3_GAME tab to read "Play Game" this is all permanent. It works, believe me!!
I just did something REALLY funky it seems. I installed Asbestos v1.5, had that error at the end where it said "Couldn't patch Lv2" or whatever. I pressed X.
Went to multiMAN (Still running 1.15.00) but it was SEVERELY slow, really laggy. Guessing with what Asbestos did. Anyhow, I did notice a new folder called "dev_rwflash" tried copying that, but it totally corrupted my whole USB folder where I copied it to. Not to mention threw in a bunch of funky looking files.
One question though, what's the difference with dev_rwflash and dev_flash? Both have the same contents, is it just being able to write to it that is different?