I'm curious at to what other's experience is. Personally, I've always had limited success with increasing my flexibility. I'll put that down to a lack of consistency.
As a general note, I've found that I get my best stretching results when I've warmed up. Not, muscular exhaustion, but something more than just bouncing before active meditation.
I've tried some of the stetching exercised suggested in SFQ II. I've had some success with the stay with it and going as long as you can. I've been impressed with the flexibility afterwards. I'll do sitting meditation in the kneeling position. I'll do a really sad looking half lotus while watching TV.
Good luck and keep us (me) updated with your progress. I may just pick up your 3 month goal. May be we can start a full lotus or bust support group going. 
You are perfection.
Iam2 
