I was able to download and install the map-pack via Mass-Storage mode. It's easy. I'll see if I can find the instructions.

But that doesn't help you type in addresses because for some reason Ovi Maps won't search without a data connection or wifi, even if you download the maps.

According to this link, Map Loader apparently works on the N900 now.

Okay, here are the instructions I followed on my N900. But if the map loader works that may be better. I wouldn't know. This worked just fine.

But the way I did it, I don't get satellite maps or terrain maps.