Install this version:
emerge -a =media-sound/setbfree-0.8.11
If this version is masked, you can unmask it using the autounmask tool or standard emerge options:
autounmask
emerge
autounmask =media-sound/setbfree-0.8.11
Or alternatively:
emerge --autounmask-write -a =media-sound/setbfree-0.8.11
setbfree-9999.ebuild