Split rims really are an area for specialist attention. We have a process which we follow for every set of splits we work on, currently we only refurbish two-piece alloys.
After tyre removal we carefully with a little heat remove the bolts from the wheels. Splits rim bolts suffer with dissimilar metal corrosion and can be testing to remove. Once apart the individual pieces are treated to the same process that standard single alloys are prior to masking as required and recoating. We then tap clean all the threads on the wheels and clean the threads of the bolts to remove corrosion if they are suitable for reuse.
For details on the full process feel free to call and speak to a specialist.