These are what I use:
Michael's template for the boxcar
Photoshop for the repainting
RSBinTool for importing the texture into Railworks
RW_Tools for editing the bin files
And these are the basic steps I follow:
1. Repaint the car in Photoshop
2. Save the repaint in DDS format with DXT3 compression and mipmaps
3. Add a grayscale mask over the DDS image so it doesn't wind up looking like it was painted with nail polish
4. Import the new texture using RSBinTool
5. Edit the bin file in RW_Tools so it references my new repaint folder and not the default folder
And that works fine. Here are a couple of other links you might find helpful:
http://railworksamerica.com/forum/viewtopic.php?f=9&t=1202http://www.trainsim.com/vbts/showthread.php?299836-How-To-ReskinAnd on the subject of the Southern boxcar Papa, here is the picture I was working off of:
http://2.bp.blogspot.com/_OLc2TjnHOgQ/TO5oqMyd72I/AAAAAAACIt4/UWgjBXycKFA/s1600/SOUTHERN+RAILWAY+Boxcar%252C+Southern+Railway+Serves+The+South+Railroad+Train+Boxcar+Macon+GA..JPGLooking more closely at it, I think I can see that the middle of the O was painted in green. But it's pretty well faded now.