both of the said packages want to install /usr/bin/lsx
Try =x11-misc/dmenu-4.4.1-r1 - the only difference is renaming `lsx' so it might as well be called stable. Or use 4.5, which had upstream rename `lsx' to `stest', and which ought to go stable soon. *** This bug has been marked as a duplicate of bug 392045 ***