> 	chmod 4755 /usr/X11R6/bin/xcdplayer
> 	and everything works fine...

You don't need to make it setuid root.

For example, mine uses device /dev/rcd0d; it is owned by group operator.
My regular user account is a member of that group.

With the operator group permissions readable I can play and stop a CD,
when I insert it.

But when the CD is not in and the group permission is not writable, I get:

 15779 xcdplayer CALL  ioctl(0x4,_IOR('c',0x4,0x4),0xbfbfdb2c)

ioctl(cdromreadtochdr): : Operation not supported by device

When I make the operator group permissions on that device writable, I
don't get that error any more. No root permissions needed (except to
initially set permissions on device and to add user to the same group).

Also, note that cdplay(1), doesn't need it writable to work either.

   Jeremy C. Reed
   http://bsd.reedmedia.net/