1.) Find an suitable image on cisco.com [i.e. s72033-adventerprisek9_wan-mz.122-33.SXJ1.bin ]
2.) Copy the image to the CF of active Supervisor by TFTP or FTP

copy tftp://IP/images/s72033-adventerprisek9_wan-mz.122-33.SXJ1.bin disk0:

3.) Verfiy the image against the MD5 and internal checksum

verify /md5 disk0:s72033-adventerprisek9_wan-mz.122-33.SXJ1.bin  
verify disk0:s72033-adventerprisek9_wan-mz.122-33.SXJ1.bin  

4.) Delete old Software on active Supervisor CF

del sw1-slot5-disk0:s72033-ipservicesk9_wan-mz.122-33.SXI5.bin  

5.) Unconfigure other Boot Images

conf t  
no boot system  
config-register 0x2102  
boot system flash disk0:  
end  
copy running-config startup-config  

6.) Reload active Supervisor

redundancy reload shelf 1  

7.) Wait for the ex-Active to come up again on local Console, sh redundancy should tell you that the ex-Active is now in Cold Standby as there is an Image mismatch. Thats ok, Image does work, so now lets swap the CF cards
8.) Reload now active Supervisor

redundancy reload shelf 2  

9.) Wait for the second System to come up again, the VSS should run again in Active / Standby Hot Mode
10.) Copy Bootimage from shelf2 (with CF of shelf1) to shelf1 CF

copy sw-2-slot5-disk0:s72033-adventerprisek9_wan-mz.122-33.SXJ1.bin sw-1-slot5-disk0:  

11.) Delete other old images form shelf1 CF
12.) Done

Not the best / Cisco way, but it should hold your Active / Standby Config in right order.