The document I linked to was specifically about controlling BOSE via RS232 serial.
Here is another newer document, that also covers controlling a BOSE system via RS232 serial. Although I don't know if this one will work on an AV18 system:[Link: assets.bose.com]
If you are looking for cut & paste guide for RS232 with BOSE, that has all the conversion work already done for you in a nice spreadsheet; I have never seen one done for BOSE before. It just really isn't that popular of a product with enthusiast.