Back in the 80s we had drums and drums of the Zeibart coatings hanging around the POL shed. There were guys who would thin it with solvent and spray it through the princess auto type undercoating gun. There were no adapters to get into the channels, but overall it seemed to work out pretty well. The guys would do it on the hoist and would come out looking like they were the ones being zeibarted.
http://www.princessauto.com/en/detai...H1UaAl_h8P8HAQ