It's really just as straight forward as you might imagine. Import the machine into Converter, select a new drive C: size, and export to the same VMware host server. Works fantastic - it's one of my bag of tricks for an otherwise difficult problem.
Hope this helps!
I simply rename the VM in VC and convert to a different LUN with the original name.
If you have to convert to the same LUN, then you should extend the existing disk, temporarily attach it to another VM and extend it via diskpart. The source VM has to be shut down of course. There are plenty of posts/documentation on this process that I am too lazy to look for at the moment. :smileyblush: