[SM5]Help needed Pop'n music theme

Hello.

I had some time ago leg broken and can't play stepmania anymore with my metal pad.
As i like music game, i've tried pop'n music on ps2 with asc controler and i like it as much as stepmania.

If you don't know what pop'n music is, it's a music game based on a 9 buttons controler:


So i want to use it to play my favorite stepmania song with it (in 2 player mode too so i can plays with friends).
I need help to make a theme and would like to do a custom game selection screen:
-4 buttons (switch to "dance" mode)
-5 buttons (switch to "pui" mode)
-6 buttons (switch to "solo" mode)
-8 buttons (switch to "technomotion" mode)
By the way is it any way to enable the creation and play of 9 buttons files ? so i could create and use all the 9 buttons of the controler

The main differences in pop'n music vs stepmania is that in pop'n music each boutton is identified on screen with a single color (you need to press the button when the white line in the button merge with the bottom screen red line) as on the gamepad and in stepmania the arrows colors depends on music rythm.


So is there any editable/theme way to do it or does it require changes in stepmania source code ?

I also tried the pop'n music moded version of stepmania 3 but it's from far not as good as stepmania 5

Thnks a lots for helping