How do I replace a file in an ISO file without needing root from the command line

I have an ISO file and I want to change the contents of one of the files in it from the command line. I know that I can use

sudo mount -o loop <etc...>
rsync -ra a b
edit b/file
mkisofs <options>

but I need a solution that does not require root permissions.

I finally managed to find an answer myself. I can use fuse to mount the ISO file, there is even a tool for this in the Ubuntu repositories:

sudo apt-get install fuseiso

Then I can do:

fuseiso -p file.iso mounted_iso/
rsync -ra mounted_iso/ copy/
fusermount -u mounted_iso

chmod -R +w copy/
edit copy/file

mkisofs <many options> -o remastered.iso copy/