Yes, you can do this but it will require some VBA. Don't listen to the naysayers. :-)
Here is how (assuming Excel 2003 since you didn't say otherwise, but the same thing will work in Excel 2007 with only slight differences):
First, draw your shape and give it a name or select it and look in the space to the left of the formula bar to see the name that Excel gave it by default.
Next, go to View --> Toolbars and turn on the Forms toolbar. Click on the Scroll bar control and then draw it on the screen. Right click the scroll bar and choose Format Control. Set the options to whatever you want, and then set the cell link to K1 (you can change that, but that is what I'm using in the VBA code).
Next, press Alt-F11 to open the VBA editor. Right click on the project for your workbook and choose Insert --> Module. In that module paste this code:
Public Sub RotateShape()
ActiveSheet.Shapes("MyTriangle") .Rotation = ActiveSheet.Range("K1") .Value
End Sub
(Note: Everything from ActiveSheet.Shapes to .Value should be on one line.) Change "MyTriangle" to the name of your shape.
Finally, go back to the worksheet and right click the scroll bar control again. Choose Assign Macro and then select RotateShape from the list.
When you click the scroll bar, the shape should rotate to the right (clockwise). The amount will depend on the settings for the scroll bar control. When you scroll to the left, it will rotate back to the left.
That should get you started. Note that you can change K1 in the code above to another cell that has a formula that changes the rotation amount. This technique can get around the limitation that the minimum value of the control is 0.
I hope that helps.
Tim
http://www.tvmcalcs.com/blog/