I think it's not the correct section (should have been posted in Script Support), anyway I'd start on adding something at public enum AccessLevel (Server/Mobile.cs).
Then you should add something in the admin gump (Scripts/Gumps/AdminGump.cs) to make these new access levels "accessible": some lines at line 145 (method GetHueFor), line 163 (string m_AccessLevelStrings), something about lockdowns at line 425, buttons from line 828, line 1738 and line 2253.
Then you have to hope it works and then you can start putting new accesslevels here and there.