Hi Evgeni,
To be honest, I don't know whether the UI (either XMLUI or JSPUI) will even provide the user with a link to edit the Item, regardless of whether he/she has Item WRITE permissions. Originally, both UIs allowed Administrators to edit items. As noted in my previous message this only began to change in the DSpace 6 JSPUI.
So, that's a long way of saying, you might need to also modify/customize the UI to get this to work. As this is not a feature that DSpace currently supports out-of-the-box (and I've never tried this before), I don't have any other specific advice I can currently offer.. Hopefully if someone else on this list has experience with this they will speak up. Otherwise, you could simply try adding an Item WRITE policy and see how the UI reacts to that.
- Tim