The ISE Compatibility Guide does not go down to the router module level, but the ISR G2 (19x, 29x, etc) reference indicates that the EHWIC-D-8ESG-P switching module does have the AAA support needed for basic ISE (802.1x, MAB) functions.
The Compat Guide does indicate limited support for Profiling and Guest features, and the module is past End of Software Maintenance so you might strongly consider waiting until you refresh the hardware at these sites to deploy NAC. If you run into any unknown bugs on that platform they will never be fixed, so this should be considered as a risk.
Also, be aware of these known bugs:
https://bst.cloudapps.cisco.com/bugsearch/bug/CSCve01806
https://bst.cloudapps.cisco.com/bugsearch/bug/CSCtt94766