They key phrase in bold:

>in pc_data or something each character would have an integer
>variable much like alignment....one for each thing you can be
>vuln/resistant to..... And in the code anywhere where a vuln
>or resist flag was set...you could instead just incriment or
>decriment the counter in the pc_data.

This is why it is a huge undertaking. If it was a small code change it'd be done already.

So long, and thanks for all the fish!