In practice, it's much less of an issue than you might think. As soon as you do something on the Mac, the iPhone change(s) will be pulled over, if the periodic sync hasn't already done so. So, if you are only working on one sequential project, you might not see the proper next action unless you tap the sync button, but as it turns out, it's a good idea (for performance reasons) to do a sync when you switch to a different device, which eliminates the issue.
If you are determined that you need to twiddle the parameters, see this post:
http://forums.omnigroup.com/showpost...34&postcount=2