The recipe to have rockbox running on some random device:
1) Take the position of lead developer as probably you are the one interested in having port done.
2) Gather as much info as possible about hardware and software. This usually involves opening the device, taking hires photos of internals, googling datasheets of components, disassembling original firmware if available.
3) Having all the knowledge from point 2 assess possibility to do the port. Main points to consider are:
- Does it have 32bit cpu?
- Does it have at least 4MB of ram?
- Do you know a way to run arbitrary code (be it some software flaw, upgrade procedure or some debug/recovery mode)?
- Does rockbox run on this hw platform already? If yes you are lucky and need to write only lowlevel target specific drivers (mainly screen, buttons, maybe codec), if no then you have to start from scratch.
4) Do the job and get the fame. Then support other interested people. Sometimes it will be you and only you who is interested.
There are some nuances in every point but rockbox developers are rather helpful so you will work it out!
Good luck