Joseph Larson, the original creator of Asciiportal, sent me this mail:
Hey, since the map select is broken on the version you ported for the dingoo, and since I don't want anyone to miss out on the fun (heh) use this maps directory. It's every ASCIIpOrtal map to date. Unfortunately I haven't checked it for repeats or completability, but hey, not like anyones going to actually try to finish all 120 levels.
You can download this levelpack from the Dingoo File Archive
To install it simply replace your maps dir.