Which version of AOLserver are you using? Not all versions support other character sets. The OpenACS distribution at
http://uptime.openacs.org/aolserver-openacs/ includes internationalization support and the recent AOLserver 4 betas should too. (There are patches for a few other 3.x versions, but you would have to recompile AOLserver.) I believe the configuration might be a little different depending on which version you are using.