Modify default Viewable By for Comments

EDIT 10/21/08: This issue can be closed. I used the workaround found here: http://confluence.atlassian.com/pages/viewpage.action?pageId=163339

I need to be able to change the Default Viewable by for Comments. We are using JIRA internally and externally with clients, and want any comments submitted by internal users to be only viewable internally by default.