First you need to acquire the source code of the game you want to port. The source needs to be written in a language compilable/executable for Dingux platform (mips Linux): C, C++, python, nLove, bash. The game also needs to be written using libraries available for Dingux, or ones which can be ported to it (so SDL but not openGL or Allegro).
Once you're sure these won't be a problem, you can start porting the game. To do so you download the mips linux toolchain
for your host platform and set it up. Then, depending on the language your game is written in you compile the game with mipsel-linux-gcc or mipsel-linux-g++ (for C and C++). You also need to modify the game's code and alter the resolution, button mappings, text strings, and all the stuff that needs to be changed in order for a good port.
Once the binary is built, you test it out and if it's ok, you release your newly ported game.
Tl;dr in order to port a game to Dingux you need:
* game's source code
* basic familiarity with programming
* basic familiarity with linux
It's that simple!