Your post would be better in the "Newbie Board" but a short answer anyway.
No and no. No it must not be in the boot.bin and no, there are no specific tools to open a boot.bin.
Every game is different and each game is normally unique on the form it is build.
The rules to find/modify/reinsert your text are basically all the same for each system so if u want to hack, go read one of the many SNES/PSX/NES/etc... beginners guide out there but u will spend the most of your time in front of an screen like this:
and if u are lucky that u have an disassembler for the PSP, spend some more time in front of a screen like this:
and the rest probably with screens like this:
Sorry if it sound a bit depressing but translations is not like translate a word document.
The most of the time u will spend it trying to figure out where the text is, in what language it is and how to open it so that u can read it. Then spend alot of time to get it back inside the game again and make the game understand what u translated. The translation of the text itself it's probably the easiest part.
Just to be curious anyway....what game u had in mind to translate??