Unless things have changed recently, only train station pick up is possible.

I saw an article several months ago about the latest generation ticket machines that have passport scanners, but I'm not sure which stations have them at present.

If you haven't already bought tickets, and aren't looking for high demand trains (e.g overnight to Shanghai), buying tickets at kiosks, including PEK might be the best course of action.

I really dislike train station will call. It's often fast, but I've had wait in line for more than 30 minutes several times so I always factor this possibility into the equation.