The only SNMP reporting activity supported by CatTools is the Report.SNMP.System summary activity: http://www.kiwisyslog.com/help/cattools/act_repsnmpsyssumry.htm
All the other reporting activities (including the Report.Version table) require login to the device over Telnet or SSH.
The Report.SNMP.System summary activity however, supports up to 5 custom OID's, so you might be able to get the version information you want by configuring these within the activity.
If you really are interested in doing this with SNMP - you might try NCM. It has quite a bit more support for SNMP and you might like some of the added functionality. You can download a free trial here.