Well,
Taskbar3 "has" the ability to create a vertical taskbar ;) But it's a little bit tricky.
Here's the setting

with which you can tell how much lines (vertical) your taskbar should have. Default is 1.
Now you only must calculate how much "Tasks" fit vertical in your taskbar

"TaskbarSpacing" should be 0, if you want space between tasks make it in the tasks itself (image), or try out what looks better.
"yourtasksheight" will be the "Tasks"Height
"yourtaskswidth" will be the maximal horizontal "Tasks"Width (less than your TaskbarWidth of course ;))
Play around to get the best looking configuration (all is possible, just try)
Wrap with autoadjust works also if taskbarlines it reached "TaskbarButtonDirection" is then the wrap direction.
I use it with taskbar3-0.306_alpha-3.dll maybe older/newer versions don't have the "taskbarlines" anymore, Taskbar3 changes it syntax so often :(

Andymon