Do you means the track zoom bar default in the left of map?
The other user tried to build a track zoom bar for the desktop edition before, but failed because the background image cannot really get transparent, so it looks bad.
If you want to build a custom track zoom bar in desktop edition, I think you can choose some other style which don't need transparent background. In fact it's a custom control, call map to zoom in/out by the slider move event, you just need to calculate the slider position and calculate its zoomlevel, then set the scale to our map. And when our map zoom in/out, you can also get the scale changed in ScaleChanged event, and you need reset the slider position.
If you met some other question when implement that please let us know.