darkshadow88 and I have been trying to get p-sprint working in Microwindows. I haven't quite been able to figure out how the modifiers (shift and alt buttons) are read in Microwindows, or how it works exactly with the scancodes (and if they are really compatible with PC keycodes - which it seems to be).
But the basics, typing ASCII characters into textboxes, we got working. Here's a version of the MDEMO with p-sprint enabled as a keyboard driver. Also included are the files you can install in your own version of the Microwindows source if you want to further experiment with it.
Thanks much to darkshadow88 for helping me with testing this, as I didn't have access to a working PSP.
(1.0 only, you'll have to 1.5 it yourself)