Thanks to Dr!fter/asherkin for helping out on IRC. The actual offsets were 656 and 658. I was using decimal math in my hex calculator which caused the error.
Originally Posted by Powerlord
I assume this includes a cs_gamerules entity for the CCSGameRulesProxy class, much like TF2 has tf_gamerules entity for the CTFGameRulesProxy class.
Presumably, you can use FindEntityByClassname and SetEntProp / GetEntProp to manipulate the team scores through it directly.
The entity is a proxy and modifying it does nothing, which is why the gamerules natives were created.
Originally Posted by GoD-Tony
Is it possible to read/write to an arbitrary offset inside gamerules?
As a follow-up, there are no natives for this, but Dr!fter has a working snippet which I'll clean up and post here when I have time.