We occasionally nebulize cats or small dogs with pneumonia, and it works very well. I have wondered about doing it for snakes. We most commonly use a mixture of an antibiotic, a steroid, and a bronchodilator in a solution of saline. I have seen straight saline used in the case of a very severe upper respiratory infection, for the purpose of softening the mucous so the cat could expel it more easily.

We use a regular human nebulizer and plug the tubing into a an adapter we have mounted to a rubbermaid tub. For those that don't have a nebulizer and don't want to buy one for a one-time treatment, Walgreen's drugstores rent them for a pretty reasonable fee...I think it was around $35 a month.