I’m not sure what your exact setup is, but the main problem is routing those public IP addresses to your clients.
As I mentioned, you will probably need to put your public subnet on a one-to-one NAT with a set of private addresses, this can be done with netmap, specifying a range of addresses with src-nat, or setting up all of the one-to-one NATs yourself. With netmap you need to feed it a complete subnet, you cannot specify a range, and for src-nat it seems to be a little random what IP address connections will use, but you can feed it whatever size range you want to.
You can also try the proxy-arp method mentioned in this post:
http://forum.mikrotik.com/t/public-ips-for-client-not-bridging/34246/1
I’ve played with it some, but not much.
There is another method that I have seen work with a different piece of hardware, so I have no clue at all if it will work here. You basically assign the full subnet to the LAN, then you assign a subnet of that that will contain the default gateway and whatever IP address(es) you want to assign to the WAN of the box. Something like this:
/ip address
add interface=LAN address=10.10.10.8/24
add interface=WAN address=10.10.10.2/29
I might give this one a try later on today or this week if I have time. 10.10.10.1 would still be the gateway for any IPs on the LAN.