I posted this same question on the DotNetNuke forums and was directed with the following answer:
As to creating the page, there is no longer anything special about pages under admin (in early DNN days, only admins could access them but this limitation was removed in dnn 3.0), so the advice at http://www.dnnsoftware.com/wiki/page/create-a-new-page-programmatically will work with you just identifying the admin page as the parent page.
However for admin pages, I'd suggest using a tabid rather than a fixed name (in case someone renames "admin" to something else) e.g. use PortalSettings.AdminTabid for the parented property when defining the tabid that you pass to tabcontroller.addtab(yournewtabinfo)
http://www.dnnsoftware.com/forums/forumid/203/postid/498252/scope/posts#498252