Once you have downloaded it make sure that you rename the 'Trunk' folder into '+Trinity' or it will not work also make sure that you delete your setting folder as well as remove trinity 2.x from your plugins folder.
Also I would like to point out that is not really a stupid question as there is no documentation on this, I had to look all over the place to figure this out and when asking this same question all I got was someone telling me to not bother with it and stick with 2.x...