Is it possible?, yes, is it costly?, can be. Any area you want the inlays put it, will require a refinish of that area, and Depending where you want the inlays a forearm is more to refinish than a butt sleeve, if there is a wrap, then it may require a rewrap. If it's wrapless, IMO, the whole cue needs to be refinished to ensure no flaking, or peeling where the different finishes meet. Can be an adventure to say the least.
Sometimes, it's just a better, and cheaper route to have another cue built with the desired inlays included, JMO.
Dave