I've installed m0nowall "wrap-1.232.img" on the CF Card. At the serial port I can see it's successfully booting up, I also can enter the IP-Address to be used, but it's not reachable over the network. Cabling is checked twice, should not be the problem.
m0n0wall 1.2x does not support ALIX boards. Try 1.3b7 instead (the WRAP image of it works fine on ALIX.2).