The Catalyst 6000 running Native Cat IOS is supported for both Sup1a and Sup2 beginning with 12.1(11b)E, and is supported by all later versions on this E train like 12.1(13)E and 12.1(12c)E2.
Refer to the 12.1E Release Notes for more information:
http://www.cisco.com/univercd/cc/td/doc/product/lan/cat6000/12_1e/ol_2310.htm
NOTE: If your switches are running in a redundancy mode, then you may want to consider purchasing a second IDS Module. The module in the primary switch will only be able to monitor traffic going thorugh that switch. If the primary switch goes down and secondary takes over then the traffic will not be monitored.
Another possibility would be to use Remote Span. Place the module in the secondary switch (since the secondary will likely always be up). Then use Remote Span to send traffic from both switches to the one module. Remote SPan is first supported in Cat IOS with release 12.1(13)E.