Update for June 2017
There is a bus every 20-30 minutes during daytime from TAPO to Apizaco by Atah if you want to avoid Puebla.
There will be dozens of colectivos around the Elektra. You are looking for the one written Teacalco or San José Teacalco, on the South side of Serdan between Juarez and Hidalgo. Price asked was 25 pesos per person, but for 200 total the driver left immediately (8 am instead of 8:20) with only my party and one local and made no stop except to drop that local.
There was only a return at 5 pm (it was Wednesday if it matters), but we could surely have arranged something with the colectivo driver if we wanted.