I use partimage (Linux). The first thing you will want to do (if you haven't already) is to clone the internal install to a SD card. Then you can just plug the SD card into a desktop/laptop and use partimage to save the image of the partitions to an image on your HDD.

If you need anything more specific reply (and if you don't know how to clone to SD, search the forums or reply and one of us will get back to you).

Anyway I prefer partimage and other such imaging techniques as opposed to dd as all it takes is one error to make it unrecoverable (and unreadable for that matter) AND it copies the entire partition including free space.