iPhone Primo 2 custom POIs and icons ?

Hi guys,
I managed to get custom POIs into my Primo on iPhone 4, by creating an user.upoi. But I can't get any custom icons.
Do you know if there is any possibility to use a ui_igo9 or ui_iphone or ui_xxxxxx folder?
Is the way how Primo iPhone uses POIs known?

Thanks for any hint