I also have the Env2. As far as I know any 'sound' in My Sounds can become a ringtone. You just have to jump through the right hoops.
(1) If you have not already done so Use the record feature to record the sound you want as a ringtone
(2) Find the sound in My Sounds and press the options key
(3) Select Send
(4) Enter your own phone number
(5) Send
(6) When you receive the message select View Now
(7) Press Options
(8) select Save As Ringtone (option 4 on the Env2)
That works for me.