if you really need that, you can see this thread:
http://forum.mikrotik.com/t/metarouter-images/28791/1
where some users did awesome work and made OpenWRT images for MetaROUTER
on later pages they are using newer releases that matched kernel that patch 1.2 was made against.
on 3rd page of that thread you will see posts of liquidcz and NathanA
where they have built images and what version they used.
for example this post:
http://forum.mikrotik.com/t/metarouter-images/28791/123
wiki page has note saying that using latest trunk might have problems while applying the patch.