从不属于ASP.NET内容页面的类访问母版页的属性

So I'm wiring up my first MasterPage, and everything is working great except for one thing. This is a legacy app, and I have an old BasePage class that all my content pages inherit. It inherits from System.Web.UI.Page, but has no content itself (no .aspx file). It runs a bunch of the user authentication/role granting menu building. I want to keep this functionality but use it to set controls on my MasterPage to build out the menus. I cannot for the life of me figure out how to reference the MasterPage properties without a MasterType declaration in a content page. So I'm wiring up my first MasterPage, and every