Hi Ivan,
A live Ubuntu or derivative such as Mint CD should work fine as it ships with JFS (and HPFS) support. In my case I just copied the files to a different partition.
Unluckily it is not a simple procedure as you have to go to the command line, mount the partition as read only using sudo and such as OS/2 JFS partitions are only accessible as root under Linux due to the lack of permissions though it is possible to add them. At the time I had to read a few man pages to learn how to do it and now forget the exact procedure.
You could use a USB stick formatted by OS/2's JFS. Linux can access OS/2 JFS but not the other way.
If the poster has a valid DFsee license, getting Jan's help is probably the easiest route. As it looks like only the journal is damaged, he should be able to recover everything except his most recent work if he was writing to the disk when the power failed.