Hook up the router to the main phone line which your Motorola is
using. You need a power adapter to start up the thing as well. I'm
not sure of the voltage and required amperage the 2Wire modem
requires, since I've never bothered to check with mine. See if you
can get a 2Wire power adapter online as well.
I'm not sure if you will be able to use the 2Wire router. Might
have been vendor-locked to Singtel.