Damn, my connect reset.. I have to retype all of this.
There is an info screen on the Roku2 (might be one on the Roku1) that will tell you your ip address, but without a remote that is hard.
If you can figure out the ip address of one of your machines on the network (NOT YOUR IP TO THE OUTSIDE WORLD), just try a few ip addresses and you are bound to get it. Dont' know how to find out on your mac, do a quick google search to figure it out.
(Your computer is 192.168.1.3, for example, so try remoku with 192.168.1.4, 1.5, 1.6, 1.7, 1.2, 1.1, etc... you will stumble on it eventually).