Just alter the material of the wall. Ugh...go into the audiobank and find the text file "material index" or something. There, you can see or create materials known by the FPSC engine. (Note: every material has a number delay, so in the index, material #1 is recognized by FPSC as #0. EX. If I want a wall to have the #8 material, in it's specs (or whatever it has) I have to configure it as material = 7). So, create a new material (Note: the FPSC model packs CREATE THEIR OWN MATERIALS! So, if you do create a material, make sure it is also saved somewhere else, just in case a Model Pack overwrites it). Give it the decal "blood". So, when you shoot the wall, it'll spurt blood. You can also change the bullet-holes accordingly.
Hope that helped!
"When all of hell breaks loose, I will be laughing at the people believing a god will save them."