Editing partition image

My Samsung phone lost its IMEI number. As far as i know it stored in /efs/sec_efs/SVC és !SVC files. These files cannot be edited during running. My idea is that i "dd"-ed the efs partition to an image file, then i would edit these two text files, then restore the efs partition from the image with ODIN (It's similar to fastboot mode on other brands). How can i edit the partition image file? 1. I wanted to mount the image file on the phone with ADB as a normal writeable partition, then edit the SVC files. But how can i mount it? 2. Mount the image file on Windows like CD/DVD/etc image files, then edit the text files. But how can i mount or edit the image file? Is there a working application for this? 3. There are lots of IMEI editor apps, but i can not trust these random apps from the net. 4. Any other idea to restore the IMEI? (I know it's illegal to change IMEI. I don't want to change it, i want to restore the factory assigned IMEI.)