Carefully, as to not get any ISO into the Cloud itself, but to get ISO just into the bamboo:
Hold one finger tightly over the bottom or top of the bamboo. Carefully, using an oral syringe or something else, (unless your ISO bottles will squirt out ISO easily, without spraying / leaking it.) add ISO into the bamboo of your Cloud (after it has fully cooled down, or else you could shatter the glass from the thermal shock of cold ISO and hot glass)
Once you have got a bit of ISO into the bamboo, cover the other end, and shake, carefully, or if you have a way to actually plug the ends without your hands, let it sit and soak.
I don't have corks or anything, so I hold my thumb over the male joint, and pour ISO into the bottom of the bamboo. Two reasons: the bottom of the bamboo has a longer shot before the restriction, and when ISO hits the restriction, it won't want to go through as there is air trapped. So, you can get more ISO into the bamboo easily through the bottom. Once it gets "full" (no more will go in, but you can tell there is air trapped) that is enough ISO IMO. Second reason for the bottom vs. the top: bigger hole, better shot at not getting ISO into the inside of the Cloud.
Once I have the ISO in the bamboo, I cover the other end with my hand, and shake. Then, I carefully drain it out of either end, back and forth, until most of it is out (hard to get the last) and I am careful to wipe both the male joint and the bottom of the bamboo with a cloth or paper towel, so as to catch the dripping ISO before I flip the unit over to drain from the other end. This prevents the ISO from trickling up the outside of the bamboo, and down into the unit when you flip it.
Once it's as dry as possible, wait longer and longer, until there is no ISO smell in the bamboo. Then you should be safe to turn on your unit.