How to add extra fields in file uploading form in elgg 1.8

I was creating a social network for foodies using elgg 1.8 and I need to modify the file uploading form so that it allows for more fields other than description and title. I found the plug-in flexfile however the author hasn't released one for elgg 1.8. Anyone has any idea how to do this? Would it be possible to modify the source code of elgg or the plug-in to do this? Thanks.