http://www.sucasamagazine.com/SWDesignQuestion/archive_Spring07.html
"After the old paint has been stripped, make any repairs to the house before repainting it, Estess instructs. Your next step is sealing the adobe house with a curing sealer. Estess’ company sells a product called Ram Seal Cure & Prime, which is a breathable acrylic sealer. He warns against PVC or PVA primers because they will cause the paint to blister.
Once the house has been sealed, it can be painted. Estess says an exterior acrylic or latex paint can be used, but again, avoid paint with PVC or PVA. This is important because walls made of earth must be able to breathe. He advises verifying with the paint manufacturer that the product is a breathable paint.
An alternative to repainting an adobe home is using an earth plaster. This might be an option even if the house contains lead paint, Estess notes. If you are interested in exploring this option, find out the local requirements and have a lead test. If the lead content is marginal, you might be allowed to encapsulate the paint with plaster, Estess says.
Because you are working with a house that could have lead paint, according to Estess, your first steps will be learning about the lead abatement program and applicable regulations."
Also search out the cable shows. I just saw something about painting adobe, but can't remember where.