Open the editor. Select the instrument in the upper left panel. Select the notes that you want to transpose by selecting the vertical lines below the keyboard. Just beneath them are various boxes that represent the layers. Select them all. The easiest was to do that is to click the "select lock" box until all six regions are colored. That way you don't accidentally convert one velocity layer and not another.
Now the cool part. There are a couple of pull-down menus above the vertical lines. Select "Unity Note" on one and "Drag all Regions". Drag the balls on the note lines, and the tuning will change. Do a "save as" so you don't overwrite your original.
I seem to recall that there is an option for using/ignoring the unity note. I'm not at my machine now. Try double-clicking the instrument and looking that the instrument properties. You should look for something related to the "unity note".
I wonder when Dave Govett will update his GigaStudio tutorial? It's a great way to learn the details of the editor. If the upgrade cost is low, it might even make sense to buy the v2.5 edition now and upgrade for free/cheap later. It's really nicely done.