Spend hours on routeros openvpn client & linux openvpn server.
http://wiki.mikrotik.com/wiki/OpenVPN
http://wiki.mikrotik.com/wiki/Manual:Interface/OVPN
Never mentioned routeros do not support static key.
it says authentication without username/password not supported.
But what if user/pass combined static key ?
I can’t test this in routeros, routeros can’t import static key,for it can’t recognize it.