Also take a look at /usr/pluto/bin/Dhcpd-Plugin.sh. This basically polls the dhcpd log file watching for device discovery to add to database.
A hack almost as nasty as this would be to mount your other dhcpd server's log directory then link it's log file to lmce's log directory so this script could still do it's thing...
Once the devices are in the database, then for smb,cifs,nfs shares, /usr/pluto/bin/StorageDevice_StatusRadar.sh polls their online status. The actual mounting is accomplished via automount (/etc/auto.PlutoStorageDevices). I don't know if or how network orbiters are monitored.
thom: a list of specific issues that prevent using an external dhcp server would be a lot more helpful than a "in short, no".