Ok, Here's the way I do it..
1) Make a quick and dirty model in Anim8or,.
2) Load the model into LithUnwrap and save the model and a UV map..
3) Paint the texture in my fav paint program Artgem and save the new image..
4) Import the model back into Anim8or and apply the UV map, resave the model..
5) Load the model back into LithUnwrap and preview it to make sure all is ok..
6) Save the model as a .x file
7) Load up Bryce
8) Load model and center it in view (making sure the image render size is 512x512) and rescale it to be as big as possible.
9) set the second cam to the same as the directors position and change the view angle to 30 Deg.
10) Resize again to make the model as close to the final rendr size as possible (this helps in the post edit phase.. makes less work)
11) load the newly renderd image into my Fav paint program ArtGem and clean up the edges and sharpen the image a bit.
12) crop the image to a good size and resave.
Voila! an Iso model render fit for gameplay.
Note: I've been doing this for awhile so I naturally have templates and preset bryce files where I only need to load the model, palce it and switch between director and cam views to get the 2 different renderings. I also have templates in ArtGem that make post production a breze.
I hope you like this quick example of how I do Iso work, Cheers!
P.S. I attached the .x model and texture, use it at your own risk.