After both the WMS and TCS had been set up correctly, I went on trying to get the stream played following the guide at
http://www.wowza.com/forums/showthread.php?9076-Re-streaming-an-RTSP-stream-through-Wowza-Pro-%28RTSP-RTP. I created a .stream file containing the IP address of the TCS in WMS content directory, then I published the stream from the Stream Manager and tried to get it playing in the Live Stream Player example that comes bundled with Wowza, inputting rtmp://my-server-ip/myapp as the server and mystreamname.stream as the stream name. The result was a "Failed to play mystreamname.stream; stream not found." message.
The TCS apparently can connect and send its stream to WMS, and this is shown in the Wowza access log file:
However, it appears that TCS is using the live application, instead of the specifically created "myapp", even though it was specified in the TCS control panel.
An attempt was made at changing the Application.xml file of the "live" application with the "myapp" one, but the error persisted.
The Cisco support team was contacted, and they found that on TCS side the stream is being correctly sent, but something is not working in the re-streaming. Also, it was noted that the deployment guide was not updated to WMS versions > 2, so maybe there have been some changes to the WMS that aren't taken into account in that document.
Finally, if this can be of any help, the WMS is running on a CentOS 5.5, 64bit.