Help on porting modem

Well, I bought an Efficient SpeedStream 5200 modem/router, produced
based on the Texas Instruments AR5 chipset.

There are many projects intended to port and run own-compiled linux on
the DSL modens, and I assume I am passionated with computer
activities, and I really wanted to compile and port my own linux to
that modem, for it to run my own scripts and servers and all that cool stuff.

As I'm a beginner on embedded linux, I still don't know if it's
possible and how to make it, but I read the "AR5 Chipset Family"
product bulletin and it says that the chipset support "Turnkey Linux
Based software. And there was another TI paper saying that the "AR5
software router package is sampling to customers now." The processor
is said to support MIPS32.

I searched the Internet and the whole TI site but I found no further
links/documentations on that chipstet. I also contacted TI, but they
said I should contact the manufacturer.

On the efficient board, there are two there are 2 empty 'sections
holes' , J5 = 5 pin, known to give serial connection for X-modem and
J4, 14 pins, unknown.
There should be a way to upload a new linux to
the board.

I've been reading and learning arround and my really main questions are:

I can put any MIPS kernel/bootloader safely on the modem?

After it boot, how can I communicate with it? It has one USB and one
ETHERNET ... and the Xmodem serial port...

Any MIPS32 code will run on the modem?

Any help, any direction, any documentation, anything, would be really
appreciated.

Thanks very much,
(And sorry for the bas english)