I hate to be the bearer of bad tidings, but I have not found a good way to do this without destroying parts.
I have "disassembled" 3 SL Pro pens, by drilling out the clip insert. This is not ideal because you could destroy the pen. At the very least this will destroy the click mechanism and the clip insert.
I 2 of my cases I made the pen of one solid piece of wood, so there was no option of separating it in the center.
In one case I was able to pull the center band out of the top part by wrapping rubber around the CB and using "gas pliers" to twist and work the CB out of the upper tube.
If you are wondering what gas pliers are here is a link with a photo. I have not purchased from this company, it was just the first one I found with a picture. My pliers are from my copier repair days and they were available in any tool catalog. I like them for gripping round things.
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http://www.crawfordtool.com/crescent.html
Hope this helps some, you just happened to pick one of the more difficult pens to disasemble.
Oh yes, one thing you need to be sure of when assembling a SL Pro, is that the CB is installed right side up. It is part of what makes the click mechanism work. The longer end of the CB assembly must inserted in the upper half, toward the push button or it wont work.