Using KNOPPIX I managed to clone the entire partition. Most likely any live linux distribution would have done the trick, but KNOPPIX was the first available to me. The individual steps were:
Initially, I created a virtual harddisk file of appropriate size in Virtual PC. Then, using the options knoppix noswap nofstab 2 I booted both, legacy and virtual PC into linux textmode without mounting the internal harddisks or creating swap partitions.
Using GNU parted both harddisks were made to corresponding sizes. This was neccessary to adjust the partition sizes, in my special case using the command resize 1 1 1996, but your parameters will differ.
To exchange data, I enabled windows file sharing in Mac OS X and mounted it in both environments using the following commend sequence:
mkdir /mnt/backup
mount.smbfs '//g5/thomas' /mnt/backup -o username='thomas%password'
Now comes the step of creating a complete image from the legacy PC. Towards that end I used partimage which was also utilised to re-create the contents of the harddisk inside Virtual PC. The commands I used were:
partimage -z1 save /dev/hda1 /mnt/backup/win95.partimg.gz
partimage restore /dev/hda1 /mnt/backup/win95.partimg.gz
That's it. Virtual PC now boots from the harddisk image into Windows 95, and all that's left to do is adjusting the hardware drivers that are used.