have there been any successful installation of m0n0wall under cable broadband

I am using roadrunner and my ip is issued under dhcp...but will never change ..I have a agreement
with time Warner Ohio and there granting me the lease time of forever ....(persay)

now I have had no success on getting this installed I have it up and running but as far as it
obtaining the ip  it does not get one


any help would be appreciated