Craig S. Mullins article applies to DB2 for OS/390 platform.
In DB2 9.7 you actually can create indexes for both DGTT and CGTT. Also you can enable logging in CGTT.
For 9.7 read here: https://www.ibm.com/support/knowledgecenter/en/SSEPGG_9.7.0/com.ibm.db2.luw.admin.dbobj.doc/doc/r0054491.html