MBR plus emulated FAT

[Csepp]

Hi!

Would it be possible to store the metadata for emulated FAT partitions
backed by host directories?  It would make installing Windows 98 much
more seamless, since it would be able to set the boot flag during
install. I have a 9front install that uses no block devices and gets its
root file system via a simple 9P server, I've found that extremely
useful, since it lets me back up or modify files directly from the host.

I don't have that much free time, but if it wouldn't be too difficult to
implement this and someone helped, I could try to do it myself.  But
honestly I would be super thankful if someone else implemented it
instead.