Gunther,
STM is only available for C6678, and a nice training/tutorial can be seen in the link below:
http://processors.wiki.ti.com/index.php/CCS_Modules_Library#Real-time_Trace_for_Keystone_Devices
(check Lab 3 for STM)
For an overall support of features per device/family/emulator, check the Trace webinar below:
(Please visit the site to view this video)
Hope this helps,
Rafael