how to let dpkg assume a package installed?

["bear" <xgl99@mails.tsinghua.edu.cn>]

hi all
       The problem comes from this. I have cvs version mplayer compiled and
installed. and I also want debian package version of mozilla-mplayer to be
installed. But it depend on mplayer-xxx which I dont want. so how I let
package system think there is a mplayer-xxx installed and do not automatically
install a mplayer-xxx in aptitude? 
       Thanks!
                                                            bear