If the DLLs on the device are included in the custom ROM, then you can go ahead and install them because they won't replace the ones in ROM - they'll just "shadow"
(override
) them. If you don't want to mess up other apps, then you can copy those DLLs into the CE Agenda folder, delete them from \Windows, and then soft reset, which will allow the original DLLs to resurface from ROM.
