You do not actually need to extract the partitions for qemu, since the operating system understands partitions just as it would on real hardware. In fact, it may be better not to extract the partitions, so that you can easily access the swap partition, and can return the image to an SD card later.
True, you don't have to extract the partitions. But you can It was rather meant for reference.
If you do wish to extract the partitions it is worth noting that they are all exact multiples of 1MiB in both size and position, as is the modern practice. This allows a much more efficient block size on the 'dd's:dd if=debian6-17-02-2012.img of=d6boot.raw bs=1M skip=1 count=75
dd if=debian6-17-02-2012.img of=d6root.raw bs=1M skip=77 count=1590
dd if=debian6-17-02-2012.img of=d6swap.raw bs=1M skip=1668 count=191
Didn't notice this, though. Thanks for pointing it out