is there an equivalent of FreeBSD memory disks and mdconfig

[David Goodenough <david.goodenough@btconnect.com>]

I ask because I have some Compact Flash images which I normally copy onto 
a CF card by mounting it in a USB CF writer and using dd.  I recently 
bought a batch of CF cards which seem to have decided on a different
definition of 128MM (they are about 121MB) and so the image will not copy
onto them.

What I would like to be able to do is to mount the image as a memory disk
(or some equivalient) and then resize it.  

This is not a simple case of mounting a partition image as a loopback,
this is the entire bootable image complete with partition table and MBR.

Thanks in advance

David