real IP and rfc1918 IP on the same machine - how?

[John]

hello freebsd-questions,

I have a workstation with two NICs - one wired (real IP address on a 
/28) and one wireless, which I want to configure to use the protected 
wireless LAN on 192.168.100.0/24. I want the internet to route through 
real IP address, and I want access to the wireless LAN. I don't want to 
route out to the internet through the wireless LAN, I just need to be 
able to contact the machines within it. The wireless LAN itself has its 
own gateway, which is not this machine but a wifi access point.

How can I configure the ath0 interface so it sees the wireless LAN but 
doesn't break routing to the outside world on this machine? Both 
interfaces will have static IPs. I have tried statically assigning ath0 
(wireless interface) to 192.168.100.100 255.255.255.0 , em0 interface to 
[real IP] and default gateway to the real IP of the gateway, but once I 
bring the interfaces up I cannot access the real IP of the default 
gateway.

can anyone help?

thanks,

-- 
John