how to wire a 2 way switches with 2 pendants
It sounds like you want a pretty straightforward lighting circuit with a 3-way switch at each end of the hallway controlling the lights. To do this, you must have 3 conductors running between the switches. The typical way to do this is to run a 3-conductor cable, such as 14/3 NM or MC cable. You can't legally string a lone wire through the attic, so pull new cable if you need it.

This answer might be helpful, and it references others.