First off, you do not want to bring the ham to 240. I assume you meant 140. Also, the ham is already fully-cooked, so I'm assuming you just want to add more smoke. Additional cooking is not necessary, and will only dry out the ham. If your goal is to add more natural smoke, then use a cold, or low temp smoke scenario. You do not need, or want to bring it to 140 during smoking. Depending on which smoker you have, that would entail using chips, maybe a pan of ice, maybe a cold smoke plate, an on/off analog dial thing, a programmed auber with ice in the chamber, or a dedicated AMPS or Big Kahuna. I have a cold smoke plate with my #1, so that's what I would use, but others here might have a suggestion for a low temp or cold smoke workaround for a non-D model. Just get some additional smoke on there as you desire (2-3 hours without bringing the temp to 140), then wrap tightly in foil and chill back down quickly. Reheat the foil bundle in the oven to 140 on your big day.