Seeking an external editor for FEMM

I was playing with the free electromagnetic field solver FEMM 4.2 just for fun, and although the simulation itself has met nicely my needs, the process of creating/editing geometric objects became clear as being something rather boring.

To get around this, I had exported in the DXF format the original drawing from a design available in the folder extracted in the installation, and then performed the appropriate changes with the QCAD trial version ( a Pcad-like tool ), but once importing back the modified file into FEMM, all electromagnetic properties of objects disappeared.

Does someone know some trick to combine an external object editor with this tool ?

Update:

I found a nice tool, MicroFEM, which according to the User Guide should be able to edit .fem files, however I had no success up to now. At attempting to open all the FEMM example drawings, it returns "invalid numeric input"

http://www.microfem.com/download/microfem-user.pdf

Still trying...