Easy.
In src/burn/capcom/cps_decrypt.cpp
Find this:
while (k->name)
{
if (strcmp(BurnDrvGetTextA(DRV_NAME), (k->name)) == 0)
{
break;
}
++k;
}
Add this after:
// Check if xor file is loaded
if (k->name && nCpsCodeLen)
{
int x = nCpsCodeLen-1;
while (x)
if (CpsCode[x] == 0)
x-=1;
else
break;
if (!x) nCpsCodeLen = x;
}
Find this:
if (k->name)
Replace it with this:
if (k->name && !nCpsCodeLen)
Then for each game, just add something like this:
{ "xmcota.xor", 0x100000, 0x1b04be6d, 2 | BRF_OPT },
Btw, I wouldn't suggest this modification. The xors do not compress well at all, this will make the sets bad in rom managers, and it's slower.