I would recommend you to learn
WeiDU. You need
weidu to update the dilog.tlk. You could, of course, do the exact same thing with
DLTCEP on your friend's computer as you've done on yours, but that will only cost you a LOT of useful time. Since you've only got the .cre-file, an item, the portraits and the dlg-file, a .tp2 shouldn't be much of a problem to code.
All information required is located in the
weidu-readme. You can also check other .tp2's to see how they works.
Btw, are you using .d-files for your dialogue-files? I strongly recommend that, and then compile it with
weidu. Much, much, much easier.