Basically, in order to make it appear medieval instead of victorian (or just out of place) you need to disguise it as a medieval design. Definitely not clockwork mechanisms, those are a staple of steampunk - rather chains and wagon wheels. Simple and rough looking mechanism - basically the opposite of ornate and lavish things you'd associate with steampunk. Think of medieval tools and designs that could be used to achieve what you want. To give a random example, if you were to make a steampunk laptop, you'd disguise it into a victorian music box casing or something like that. If you want to go medieval on it, it becomes much trickier since the gap is a lot bigger. I can't think of anything on the spot that would be a good match.
But, since these sets are fantasy medieval, anything is game really, so you don't necessarily need to bother making big alterations.. A victorian looking contraption in a witches' lab is not an uncommon sight.