I know this reply comes well after the fact, but I just ran across this scenario today myself.
tt = that._drag.tooltipDiv,
//Temporary way to access tooltip element
val = e.value;
+ val +
In this example, I'm getting a reference to the tooltip element from the internal "_drag" property on my Slider during the slide event. Generally speaking, it's not a good idea to use internal APIs (those prefixed with "_") since they can change in future versions, but this might give you a short term solution.
Hope that helps. We'll try to provide a better official path for this type of customization soon.