Ataco, or more formerly known as Concepción de Ataco, is very easy to come and go from. Buses pass by the edge of town in front of the Parque Ecologico San Francisco – although you wont find this park on google maps (see photos).
From San Salvador
To get to Ataco by bus from San Salvador take the 205 from the Terminal de Occidente to Sonsonate. Then change to the 249 to Ahuachapán – which will pass Ataco along the way.
From Juayuá take 249 heading to Ahuachapán. This bus passes Ataco after about 25 minutes.
From La Libertad (El Tunco, Playa Sunzal, El Zonte, La Mizata)
To get here from the coast take the direct bus from La Libertad at either 6am, ~1:45pm to Sonsonate. This bus will pass El Tunco, Playa Sunzal, El Zonte and La Mizata and takes about 2hrs. Then the 249 to Ahuachapán which will pass Ataco along the way.
From Santa Ana
From Santa Ana take the 238 bus to Juayuá. Walk two blocks from where you are dropped off to the bus stop next to the Scotia Bank and wait at the corner. Take the 249 bus heading to Ahuachapán and get off in Ataco. Alternately, go to Ahuachapán first and then switch to the bus heading to Sonsonate which will pass Ataco on the way. Trip time is about 1hr 45min in total. Both buses leave the Terminal Francisco Lara Pineda.
We went from San Salvador to Ataco on December 2019 as you suggested here and it’s still working. We payed 1.3 from San Salvador to Sonsonate because it was AC and with less stops.
The owner of my hotel in Ataco suggested me to go to El Tunco via Ahuachapan instead of Sonsonate. So I took a local chickenbus from Ataco yo Ahuachapan, a Mototaxi to the new bus station, and then bought a 1.50 ticket for the 202 Especial (with stops and AC, but it stopped only once ) to San Salvador. Dropped of at Ceiba de Guadalupe . Then crossed the road and took the minibús 102A as you published. It was fast. This happened on April 17th, 2019.
From Santa Ana to Ataco vía Ahuachapán it took us 1,5 hour, and we even let the first bus from Ahuachapán to Ataco go because it was really packed when we arrived.
In that second bus the bagage rails in the bus were too small for our backpacks (only time that happened), but in that case you can put your stuff in the back of the bus.