Celestia doesn't understand Access format, so you'd have to translate it into SSC catalogs or a replacement for Celestia's stars.dat binary file.
I assume you mean an Addon which replaces Celestia's information about real stars with a database of imaginary stars with planets.
I know that people have discussed this and have written programs to make it easy to generate those databases, but I don't know of anyone having published a complete Addon.
One of those programs is described in the thread
viewtopic.php?f=6&t=13322&st=0&sk=t&sd=a&start=0 There was a specialized version of Celestia created a few years ago which included its own database, but I've managed to misplace the link to it.