There is a feature request opened for such case, https://jira.atlassian.com/browse/CRUC-1058, but it doesn't seem to be a highly demanded feature so I won't expect that to be implemented soon I am afraid.
I haven't tried that personally but I can see there are some tools on the market to migrate MKS into other SCMS (git, svn, perhaps others) which are supported by FishEye/Crucible. Perhaps you want to give a try? For example you could try seting up a on-the-fly migration from MKS to git/svn and index that git/svn mirror of your repository? Take a look at:
Hope that helps,
Badges are a great way to show off community activity, whether you’re a newbie or a Champion.Learn more
Get started on Stride in 3 easy steps If you’re new to Stride, welcome! We’re super excited to have you aboard. Stride is easy to use and set up, so don’t worry about reading tons of borin...
Connect with like-minded Atlassian users at free events near you!Find a group
Connect with like-minded Atlassian users at free events near you!
Unfortunately there are no AUG chapters near you at the moment.Start an AUG
You're one step closer to meeting fellow Atlassian users at your local meet up. Learn more about AUGs