Yes you can: go to Edit|Preferences. Choose the Lanching Tab, click on the "Set..." button. Scroll down the list that is presented then and you'll see 10 custom editor choices you can use to specify any additional editor you like. Just browse to the executable of the editor and set it. In your case you could set up one for "Capture NX" and the other for "CS3".
HTH,
Hayo