Not right now.
SoFo is enhancing Vegas scripting and I remember someone saying that this feature (controlling FX params) is on their todo list - it's just that it can appear in 4.0c or 5.0 or ... who knows. Whenever it's ready.
BTW, it's funny why SoFo does not use minor release numbers, i.e. there is no Vegas 4.5 with HD support? Instead, it's Vegas 4.0b. Such feature deserves noticeable version upgrade.
Too bad... but good to hear that it may be in the works.
I started making a script to simulate the shake of an explosion. I've done it manually a few times but a script would be an imense timesaver. The shaking was no big deal to script, but now I wanted to add linear blur with the correct angle and amount for every frame. Can't do it with presets...
The scaffolding for scripting individual effect parameters
has recently been worked out but, since it requires changes to every
effect, it won't make it into 4.0c... probably 5.0.