I'm glad I found this thread. I've remade my Trainz time completely around reskinning locomotives so I have gotten pretty good at it (if I do say so myself). Anyways, here's a few of my reskinned locomotives...
Strasburg #90 (as fictional Mount Morris #90 for a railroad I had dreamed up. I also have it in her current Strasburg scheme).
http://i.imgur.com/1YYMm4Z.jpg
Grapevine Vintage Railroad #2248
http://i.imgur.com/oL062yL.jpg
Locomotives #14 and #18 on the Arcade & Attica Railroad (with special guest Viscose Company #6)
http://i.imgur.com/WgutYfm.jpg
That last one was supposed to look similar to this photo...
http://www.railpictures.net/showimage.php?id=288953&key=7197854
And my biggest accomplishment, a complete kitbash of several different (payware) locomotives to replicate Bessemer & Lake Erie #643, currently stored OOS in McKees Rocks, PA
http://i.imgur.com/MWB7tEN.jpg
Tell me what you guys think!