Virtual Boy -
You can't automate FX in CWPA9 - just volume and pan. You need to upgrade to Sonar to get automated FX.
While you can record/automate volume fader movement in CW PA9, I would highly recommend that you use the volume envelopes. They are more intuitive to use, easier to control and, most importantly, visible as to where they are on your track(s).
As for getting around the FX automation limitation, the only thing I can think of is to cut the section of the track you wish to make the change to, and paste it into a new track. Then you can use different FX settings for the two tracks. This won't help, however, if you want to accomplish a gradual change. Maybe someone else has some better ideas.
Also, be aware that although Sonar does have automated effects, the automation can not be used for every effect. The effect has to be specifically written to take advantage of this capability. There are about 7 - 10 of these that are supplied with Sonar. To date, I do not know of any third-party plugins that can be used this way (although they may be coming in the future).