The repository won't work out-of-the-box with Maemo Mapper. The lat/lon are specified in degrees (as opposed to Maemo Mapper's and Google's format, which uses a grid-based coordinate system based on the mercator projection). Also, the zoom doesn't match up with Maemo Mapper's, so some conversion would have to be done.

If they have a WMS-based version (which looks a little similar to the URL you posted, but not close enough to identify it as WMS), Maemo Mapper can support that (with the additional "proj" package installed). Otherwise, it doesn't look easy for Maemo Mapper to support that particular URL format, I'm afraid.