I would like to use the spare IP given to my by my ISP for the guest Hotspot I run.

I use an ADSL modem to connect to my ISP, and my Mikrotik connects to the modem using PPPoE.

My ISP gives me a /30 (2 usable static IP addresses)
61.xx.yy.176 ISP Gateway Address
61.xx.yy.177 address for router (Mikrotik gets this IP address when connected using PPPoE, and NAT to all users on LAN)
61.xx.yy.178 spare address
61.xx.yy.179 Broadcast Address
Netmask: 255.255.255.252

How can I use the spare address (61.xx.yy.178)? I would like my Hotspot user traffic to use this IP address.

Thanks

WIth help from this post: http://forum.mikrotik.com/viewtopic.php?f=2&t=52997 I solved the problem.

Removed my masquerade NAT config, and replaced with two 'src-nat' rules for the two IP addresses and private & Hotspot subnets.