How can I create a line in ArcGIS 9.3 to a specific length?
I click once to start the line where I want it, and then I want it to be, say 10 Meters in length ... Similar to AutoCAD.
After you click to start the line, right click to open the edit tool's context menu. On this menu is a button named Length. Clicking this button opens a dialog that lets you set the length of the line segment. There is also a button for doing Direction/Length.
After you click the first time you can either use the context menu as Zachary suggested or what I find quicker is to use the shortcuts: Ctrl + L for Length Ctrl + A for angle (or direction), Ctrl + G for both at the same time and F2 to finish the sketch.
When you digitize the polyline
Here is a tutorial: https://youtu.be/CvvCH8Ze7m0