Emerson Exchange 365

First, you should create a custom alarm banner by saving the standard banner as a new file.  

Then in usersettings.grf, point to the custom alarm banner. In Usersettings.grf look for the  ALARM BANNER WINDOW INITIALIZATION section and edit as per the instructions.

You can do whatever you like to your new custom alarm banner.

To actually replace the bitmaps, right click the bitmap object and select 'Load Image' --> 'Primary' or 'Secondary'  for the various push button states and select the image you want for each.