Most here run them attached to glasses, in front of the ears around temples. Not truly binarual as there is no outer ear pina effect, but still head-baffled and often better for direct speaker playback of music than true binaural recordings which work best over headphones.
For true in-ear binarual, one option is using foam ear plugs to hold the mic cables (and thus the mics) in place. Basically the mic cable goes into the ear canal along one side of the ear plug, turns 180 degrees around the back end of the plug and comes back out on the opposite side of the plug, with the mic extending a half-inch or so beyond the plug, more or less right at the opening of the plugged ear canal.
Benefit is good mic positioning, damping of cable microphonics, and low cost. Drawbacks are ear-plugged listening while recording, and needing to make a relatively tight bend in the cable near the mic.