If you don't have my SVCD pack, just bbMPEG then copy the bbmpeg.dll file to your flaskmpeg directory and rename it to bbmpeg.cm.flask.
Press the select output button and the bbMPEG Encoder.
Then press the FlasK It! button. You'll then be presented with the following window:
Here bbMPEG shows you what you're going to get. It usually complains when you set the wrong resolution, bitrate, etc. So change the settings press the Settings button.
Then go to the Load and Save Settings tab and select one of the pre-built profiles. For VCD this is all you have to do, for SVCD you might want to change the bitrate settings according to your calculations. If you want to change the settings for SVCD just click on the video stream tab:
You can also go to the audio stream settings and lower the audio bitrate if you desire. Once again, this is only possible for SVCDs.