can't really answer your question how to exactly help your catasetum through the winter season cause here in my area is hot and humid throughout all year round.
but basically this is what i do for dormant plant, minimal watering, sometimes i even wait for them to shrivel a little before i water them again. if you plant is in plastic pot packed full with sphag moss, extra careful about watering them during the dormant phase. rule of thumb, its easier to kill one catasetum by over-watering rather than under-watering them.
However i did read form the net before where you need to keep them above certain temperature. can'r recall from where, perhaps you can try to Google it. any perhaps some other forum member who are growing catasetums in temperate climate would be able to help you out here.
i had raised several catasetums from compot so far, easy to grow.