Take a look at:
http://www.cisco.com/univercd/cc/td/doc/product/voice/respond/res12/admin12/e911ccm.htm#1061117
"Table 3-1 Emergency Call Route Points"
You can see that there is a 2nd CER server in case the first fails, and the failover is simply configuring the CFB,CFNA,CFOF numbers to point to 912, which is the 2nd CER server.
You could simply change this to 9911, or whatever, and make sure the CSS of the CFB,CFNA,CFOF does not include the partition of the 911 CTI RP (otherwise it will loop).