Two formatters in one field

I have node with image (file field). I need to apply two formatters on it:
* lightbox2 formatter
* download_file formatter
You know, so user could see miniature, and click on it to get bigger version, or click link under it to download full size.
I tried to write my own formatter to bind these 2 together. But failed. Can't google enough information, so if you are about to tell me RTFM, OK, great, plz link me to proper parts of proper friendly manual.

I need any pointers or methods to do it. And I can't really make it 2 fields unless I'll have a way to get them synchronized, and only one editable for an user.