How can I convert an Unmanaged solution into Managed solution?

Hi,

I have a solution file (.zip) which contains an unmanaged solution from our supplier. I also have an access of the instance of the supplier's CRM instance, but that instance doesn't show up the solution in the list as it is unmanaged one, and hence I am unable to export it.

It seems the supplier created the solution on other system, and exported it as unmanaged, and then imported that solution to the system on which he has provide access to me.

I want to import the solution to my target system but as a Managed solution.

Is there any possibility of doing so?