two options, depending on what your needs are... diald has the capability of "dialing on demand", so that the first request for a web page, ftp site, whatever will trigger it to automically dial and establish the connection.
if you want to explicitly control the connection, you need to setup a user account on the box so that you can ssh in, and then setup sudo, which will allow that user to execute pon/poff as root without giving them complete root access.(as mentioned earlier) -mike
