We just set up an Endian system at our office (still not working 100%, but not sure if that's Endian's fault at this point).
Set your ADSL modem to bridged, and then set the Endian to use PPPoE, put in your PPPoE login information, and check the box for additional IP addresses and add them in there.
Just put in your .145 to .149 addresses, should work. Might be able to use the "router" address too, but we haven't tested this.
At least, that's how ours is set up...
Are you able to then assign the extra IPs to PCs? Or are you port forwarding to that PC's LAN IP?