it is very simple
1. write the new firmware as per instructions.
2. go and change the language from settings (this is tricky if you do not understand russian, but take an android phone and follow the same steps, little bit like playing blind chess)
3. boot in the recovery than use the root update.zip to update the root.
4. install after the titanium backup.
5. install stericson busybox
6. run titanium backup than remove the fbreader
7. install the new fbreader with english icons I provided. at this stage will forceclose on you.
8. reboot or reset.
9. on start run fbreader. new english Icons will be showing.