I have those things mapped to hardware keyboard for whole Maemo (just like keys F1-F12), but it doesn't work in dosbox (while more exotic things - like mentioned F1-F12 - are working flawlessly, without even using dosbox's mapper).
Even after loading the rover.sys keyboard layout, the numbers are still not detected by some games. For example, the GoldenAxe for DOS shows a text screen to select the graphics mode just before starting the game. It is not possible to select any of the options with the numbers, they are not detected by the game. However, in the dos prompt the numbers are correctly written.