DON'T hard-wire them together. The voltages etc won't match.
One of the members here designed a custom cable that acts as an adapter between a TiVo and most DTAs (see http://grayeng.net/TiVotoComcast.htm) but I have no idea if it would work on on your FIOS box.
One of the members here designed a custom cable that acts as an adapter between a TiVo and most DTAs (see http://grayeng.net/TiVotoComcast.htm) but I have no idea if it would work on on your FIOS box.