Bypass a three-way switch for the next single pole switch in the same circuit to work on a different light?
A 3 way switch is typically wired with 3 conductors plus ground.  Ground and return are never interrupted by the switches.  Hot is fed into the first switch which then energizes one or the other of the two remaining wires (travelers).  The other switch then determines which traveler is connected to the fixture.  If the light is off, the switches are set to different travelers (first switch energizes traveler 1, second connects fixture to traveler 2).  Flipping either switch turns the fixture on by setting both switches to the same traveler.  

You need to pull a constant hot for the standard switch, so you need to source that from either a different line (may have to be same breaker for code) or from the beginning of the 3-way switch setup, before the travelers.