There are several books that _may_ have plans for a router lathe. I'm waiting for one of them right now.
Router Magic: Jigs, Fixtures, and Tricks to Unleash Your Router's Full Potential by Bill Hylton,
Binding: Hardcover Publisher: Rodale Press, Rodale Pr
1996 Date published: 1996
ISBN-13: 9780875967110 ISBN: 0875967116
Routers (Collins Good Wood) by Jackson, Albert; Day, David
Binding: Paperback Publisher: Collins Date published: 05/08/2002
ISBN-13: 9780007139781 ISBN: 0007139780
These were recommended to me by one of the forum members.
However, you might examine how deep you're going to go into this. There is a discipline called "Ornamental Turning" that produces work in a variety of materials which are router lathes on steroids and hallucinogens. Ornamental Turners International Holtzapffel.org - A catalog and history of Holtzapffel lathes - Home
The Holtzapffel Lathe is the mechanical marvel of the 1st and 2nd millenia. How someone could conceive such a convoluted contraption I don't know. Genius comes in a variety of flavours and this one's a beaut. One wonders if Einstein and Hawking studied Holtzapffel to expand on the theories of relativity.