I'm still not sure what you're trying to achieve, but at least box.net seems to offer access to its cloud storage via the fairly standard WebDAV protocol. So what you're probably looking for is WebDAV support for Maemo 4. (If Maemo 4 is really what you're still using. Are you on an N800? N810?)

A quick search brought up some half-baked solutions that seem to have worked, but were difficult to install and required some background knowledge. Once you managed to get WebDAV on your device, ask google for box.net webdav in order to find out how to configure the access.