I came around
Frank's Wiki, that has a good guide to gain shell access to these devices. He even got some Hello World programs running and told how to cross-compile applications for the device.
He couldn't discover the root password but he explains how to change the user/password quite simply, changing the sh script that runs during firmware update, or chaging it in the firmware package itself.
To gain shell access though, you have to connect the reader as a USBSerial device. You should take a look in his Wiki, but I can say that my Alfa, running the firmware from the l337 guys couldn't come up with the usbdebug file method.
To connect it in USBSerial mode, I had to boot the device while keeping the 6th and 7th buttons pressed (Previous Page and Next Page). Keep in mind that while the reader connected to my computer as a USB Serial device, there is no information about it in the screen: it shows the normal menu, with the sync option dialog (I chose not to sync, though).
Everything else went according to Frank's guide. He also has some good links worth the read, though some are in german and I had to use Google Translate to read.
That's it for today. I will keep messing around with it, and may post more info here. If someone has the same device and would like to talk about it, ask questions, shred some light or just chat, it will be nice.
And pardon me for the lousy English
Cheers!