Hi I'm new at the forums but been reading a lot recently. My sister have bought an onyx and we have been able to install a dictionary. the format is stardict:
stardictionaries and to install it we simply put the dictionaries in the dict folder of the sd card and the run the update. Two mayor issues: The boox don't recognize html wich is present in the dictionaries; The search is a little bit slow and sometimes the screen keeps refreshing several times.
The great thing is that you can change the dictionary you are using without unselecting the word.