It _could_ be done of course, but it's probably not a practical alternative. As has been mentioned, inlays are usually done when the cue is still oversized. In most cases you'd be better off having a new cue built and either sell the older cue or keep it as an extra, or a break cue or whatever. If the cue was beat up a bit and needed a refinish anyway, maybe, but the cost of refinishing the cue on top of the inlay work, done after the fact, seems to me impractical.