http://is.gd/uc87lg2 More info on my blog at http://blog.wapreview.com/16898/
I don't know about the LG 840G but with most phones you can install the modded versions over the original without deleting the old one first. When you do that you get prompt asking if you want to keep the old version's saved data. Say yes and your bookmarks, and in most cases saved passwords will be preserved,
Also you can back up your bookmarks before installing the new version in Opera Mini using Settings > Opera Link. Then after updating log into Opera Link and you bookmarks will reappear. With UC Browser use App > Gallery > Online Bookmarks to back up your bookmarks before updating and restore them after.