On http://www.vtwm.org/, there's a newer version of vtwm available - 5.4.7. In tree, there's 5.4.6a. - The URL in portage for vtwm is wrong. - 5.4.7 might be the really last version of vtwm, as upstream is dead (like in died. See http://www.vtwm.org/) Compilation of 5.4.7 is not possible with the 5.4.6a ebuild, though :(
Adding a DEPEND on media-sound/rplay should be enough to use the .6a ebuild for .7
Fixed. Thanks for reporting!