How can we use mxconvert.exe to convert a project folder?

Since mendix 6.4 there is a tool shipped with the Mendix modeler, that can do Mendix conversions. Thanks! It seems to work only with MPK. Can Make it work with a full project Folder?

> mxconvert "E:\Mendix Project\TestMx6.4.1\TestMx6.4.1.mpr" "E:\Mendix Project\TestMx6.6\TestMx6.6.mpr"
This is MxConvert, version 6.6.0.

Conversion failed: The input file 'E:\Mendix Project\TestMx6.4.1\TestMx6.4.1.mpr' is not an mpk file.

Try to update project folder:

> mxconvert "C:\temp\TestMx6.4.1" "C:\temp\TestMx6.6.0"
This is MxConvert, version 6.6.0.

Conversion failed: The output must be a directory because more than one input file or an input directory is specified.

The help shows we can use input options.... but not what the options are. Does anybody knows?

> mxconvert -h
Usage: mxconvert [OPTIONS] INPUT... OUTPUT

Converts the INPUT project(s) to Mendix version 6.6.0 and stores the result in
OUTPUT. INPUT can be a single file or directory, or a combination of multiple
files and directories. When INPUT is a single file OUTPUT may also be a single
file. Otherwise OUTPUT must be a directory.

 Options:
  -h, --help                 display this help and exit

 Exit status:
  0  if OK,
  2  if parsing the command line options failed,
  3  if the conversion failed.

Thanks

Andries