Hello,
I was given a task at my work place to develop an application. After several
days, I discovered that the application have already been created in .NET but a
Java version is needed due to deployment problem on the required OS.
Now I thought of a scenerio where the .NET application would run on the Java
platform and the Java "wrapper" would now be deployed in wherever it is
required, ie deployed as a Java program but with a .NET core.
How possible is that?
Specific steps taken towards this should be clearly stated.

Very, although I doubt very much this is what they really want.
Remember, .NET ties you to MS Windows (not a pretty option), and they're
probably trying to get away from that dependency.

Also, you would need to run 2 app servers: J2EE for the wrapper, and
.NET for the original framework.

Your best bet: find a way to translate from the original language (you
didn't say what that was) to Java. Also, do you have to integrate the
application into something larger, such as a Portal?