To Select an Icon for a Tool

In the Customize dialog ( File > Settings > Configuration > Customize ) , click the Tools tab.
Expand the User Tools section and expand the open DGN file.
Expand the toolbox containing the tool for which you want to select an icon.
Select the tool for which you want to select an icon.

If the tool's Icon property is not visible in the Properties pane, click the arrow on the right side of the General Settings tab.
Click the button to the right of the image of the icon.
The Define Icon for Tool dialog opens.
From the Look for icons in list box, select the source of the icon.
(Optional) If you chose Import Selected Icons or Import Selected Bitmaps from the list box, click Browse and navigate to the source of the icon.
(Optional) If you chose Applications from the list box, expand the list of MicroStation toolboxes.
In the Select an icon from the list below list box, select an icon.
Click OK.
The icon file is assigned as the tool's icon.

You may want to edit the icons in a DGN library or icons from a user interface modification (.m01) file that you have imported into a DGN library. First, use a key-in to export the icons from the open DGN library to a directory. You will need a separate icon editing application to edit the icons. Then use another key-in to import the icons from the directory back into the DGN library.