Well Taskbar3 has commands to allow scrolling, TaskbarShowPart prev/next it works just like VTray's scrolling, but without the option to set a step value.

MaxButtonCount doesn't disable scrolling, i can have 4 icons display properly horizontally and if there is >4 tasks running I can use LsBox shortcut buttons to call the !TaskbarShowPart bangs and scroll perfectly.

It just doesn't display >1 icon fullsized vertically using TaskbarLines.

I'll have a look at those links..