Ok. Solved my own problem. For the record a small how to:
Boot a normal 7.0.1 system in Mini vMac. Do the MacTCP stuff, so change IP address. Then copy this System to a 800k disk in MiniVmac, but without the Finder. Replace the Finder for miniSubstitute on this 800k disk. Mount this file in Basilisk II and copy the map to a share you can reach by a machine with a working 800k floppy drive. Copy the map to a empty floppy and you are done.
I have a .dsk with both a system with normal finder and miniSubstidude finder on it so I can fiddle around.