Problem :
I have a full dd of my hard disk which has 3 partitions, how can I using this image only restore a specific partition?
Solution :
You can loop mount individual partitions. I have done this quite a few times but this blog and similar one you can find on net give you clear step.
http://madduck.net/blog/2006.10.20:loop-mounting-partitions-from-a-disk-image/
The key is to find the offset of your partition in the image.
This man page for bochs is likely more permanent
http://bochs.sourceforge.net/doc/docbook/user/loop-device-usage.html
kpartx will allow you to use device mapper to map the partitions within the image to distinct device nodes.