`.../downloads/$distro/...` - `$distro == cooker`, customize this param `cooker, openmandriva2013.0, rosa2012.1, ect..`

Looks good:
`lxc-create -t openmandriva -n rosa0 --arch i586 --release rosa2012.1`

and url will be `http://abf.rosalinux.ru/downloads/rosa2012.1/repository/i586/main/release`