I believe you can NOT break down your normal PLAYING cue to remove the shaft to connect a jump handle. I believe this falls under the area of concession of a game.
BCAPL Rules
1.44 Concession of Match
When your opponent is on the hill, if you make a motion to unscrew your playing cue stick during your opponent's inning you lose the match. (AR)
1.44 Concession of Match
1. Situation: Players A and B are both on the hill. Player A, having broken the final game of the match with a break cue and not pocketing a ball, retires to the chair. While Player B is at the table, Player A, having their playing cue standing by, unscrews their break cue to put it away.
Ruling: No concession. The cue stick Player A unscrewed was not their playing cue stick.
Mind you this appears to be more when your opponent is on the hill. I think the advise is to let your opponent know BEFORE you try.