Multiple IP on WAN

Hi there,

 I have 8 ips with my isp and would like to use PPPoE on my
linksys router.. I can do this but for 1 ip.

Is there anywhere that I can set a local ip eg 10.0.0.1/8 and then
my isp ip range which is say 123.123.123.1/29. One IP is a dedicated
router IP and I would like that ip on the pfsense router. It can be
done manually if I ssh into the machine, but cannot find anywhere to
add another ip to the WAN interface.

I hope I explained it clearly.

Any ideas?

Many thanks,
Chris