This extension requires the Editor Guidelines extension so please download that first fromhere.
This extension adds three commands to the code editor's context menu (right click)for managing editor guidelines. This means you don't need to edit the registry to add or remove guidelines or to change their color.
One this extension is installed, open up a file for editing and move the cursor to the last character position on a line where you want a guideline. Use the column indicator ("Col") in the status bar to ensure you get the exact column number. Right-click (or press the context menu key on your keyboard) and select "Add Guideline". A guideline will be placed in the column to the right of that position.
Follow the same procedure to remove a column line.
Updates for June 11th 2010: