Here are the directions to the hot springs I wrote about in my trip report.
1) Turn south off Hwy 3 on the dirt road that leads to La Esperanza, Bruma, and L.A. Cetto
2) Continue on this road past L.A. Cetto and La Casa de Doña Lupe
3) The road forks a half mile or so past Doña Lupe's - take left fork
4) Continue on the road for approximately 3 miles
5) The road is blocked by a chain at Federico's where you pay 30 pesos per person to continue.
The hots springs are about 2 miles from Federico's. You can park your car there and start hiking or you can continue driving about a mile further down the road to another parking area and start hiking from there.
The road from Federico's was easily navigable although you do have to cross the creek twice.