You can use RRGGBB values (as you would in HTML) by prefixing them with &H in a foreground or background command or tag. For example in ASL,
foreground <&HFF0000>
is red. You can specify values in hexadecimal between 00 and FF.
You can completely customise room descriptions - see "How to Customise Room Descriptions" in the help file or at
http://www.axeuk.com/quest/developer/as ... ptions.htm