Emerge to previos version for programm

[smuryginim]

Hi, all.
Excuse me for my stupid quastion, but how can i go to the older version of some programm with emerge

For example, i need a version of qemu-kvm-0.14.1-r1
In my portage last version is qemu-kvm-1.____

How can i emerge version of qemu-kvm-0.14.1-r1

[krinn]

emerge =program-versionyouwish
or add all versions > the one you wish to package.mask so portage have no other choice