i was finally able to figure out how to install an english version using the japanese orig:
- download the japanese iComic007 from googlecode
http://code.google.com/p/iphonecomic/
- unzip the iComic007 pack and copy the whole iComic.app folder into your phone's
/applications folder directory
- create a new folder named Comic in var/root/media/ so var /root/media/Comic is the folder wherein you put all your zipped comics/documents
- change the permissions of all the files inside the iComic007.app folder. (i use mobilefinder in the phone)
- respring your springboard
- then to get icomic in English, delete the japanese.lproj folder directory under /applications/icomic.app
- repsring again and you will find that iComic is now in perfect english! 
* thanks kurosagi for showing the psp tool to convert documents into jpegs. works great!
* for those who have ebooks in pdf formats, you can manually convert them into jpegs by using photoshop. just drag the pdf file into photoshop and when it asks you what resolution you want the document image to be, make it between 100-150dpi only (it's only text anyway). then save it as jpeg (it automatically flattens the file to make the background white).
regards,
m.o.r.