Documentation is available as PDF on the sourceforge site.
For what it is worth, on Windows Mobile (PPC, ...) platforms, you can use a Port Splitter. A free one is here. It may solve some issues in some cases. A port splitter allows you to share a port accross applications
German users may want to read on
http://www.haased.de/gps_ge/bt747_installation_pda.html
or
http://www.die-ritters.de/blog/holux-m-241-und-bt-747.sturkopf .