Blacksmith of course

Load The item, when lkoaded clear the difuse, then paint with black where you want the mask

or

Photoshop  if you want something special, use the path tool, stroke it with black

Save

now the tricky part and I hope I can explain right:

In poser:

Color math multiply with main texture, you will use this later:  Colormultply will give you the original with the black mask (white is 1 black is zero)

turn the mask in to a negative:  math functions multiply with mas as input and multply by -1

run the result into math fuctions add and add 1 to the result of the previous step, you now have the white mask on a black background

Run that output into color math  multply

   if you want to add a texture plug it  into second input 

or  just  change the second color tab

Then to put it all together:

 Color Add the result of the first operation with the result of the last operation and plug into diffuse channel

I hope that akes sense :D

Bill

People that know everything by definition can not learn anything