I just saw this post. However, if u still in Guatemala go into facebook and search "Pata de Chucho" or "Kashem" . I also have some friends that live over there and have done some climbing with me. Hope this info. Helps ;)
There are climbing clubs in xela and Guatemala City. In Xela go to the used book store and ask about the gym. La Muela is a kick ass sport area. Make sure to go on Sunday for the craziness.
My girlfriend and I are going to be in Antigua studying Spanish from 1/10-2/8. We would love to get out and climb at Lake Atitlan, La Muela, or wherever.
If anyone is going to be around and wants to climb on the weekends, shoot me a PM. We're both competent leaders and belayers.
I was actually a climbing guide in Guatemala! PM and I can give you the name of a friend who might want to climb. There is Climbing in Amatitlan (best and most routes), Atitlan, La Muela (outside Xela) and in some secretish spots outside Antigua I have been told.
For amatitlan you just need to show up an camp For La Muela in Xela I recommend contacting Victor the dude who bolted everything... I added his contact info in a comment in the guatemala section of MTN Project.
As for outside Antigue there was an American doing some bolting there while working for XO tours. He did not have nice things to say about XO but maybe ask them for some beta.
Go to La Muela on a sunday for a truly crazy and unique experience. Hope you love Guate as much as I did :)