How do I change programs in Studio Instruments (or Dimension Pro for that matter)?  Using X3 Studio.

Like many sample based plug-ins, there is no notion of a program change command other than the program browser built into the plug-in.

One way would be to change in the track panel:
 
http://www.cakewalk.com/D...ginners.06.html#563395

Not sure if that would work in dim pro or studio instruments since i never had reason to try. 
 

What I meant was changing it in realtime in the Event List.

Sample based synths do not change programs in real time because the time loading samples would interfere with real time playback.

King Conga
What I meant was changing it in realtime in the Event List.

why?  you could set it up to send to different MIDI channels to separate instances of Studio Instruments or Dim Pro, but why not just have separate MIDI tracks?  what do you need it to change "realtime" for?

I use different MIDI channels within the soft synth.  I know that is not exactly what you were looking for, but it works.
 
You can also have another instance on another track if you need more than 16 changes.
 
This is a very common technique for string libraries in which you need multiple articulations available in a song (like tremolo, pizz, legato, marcato, etc.).  I prefer controller's or keyswitches but that doesn't work with every library. With all these solutions, unlike an old hardware synth, you have to load all the sounds into memory before you start the song.