What do you mean you dont have the means to PNF. You use your own body. I dont buy the cant get flexible thing. Anyone can, and in a short amount of time. I used to be super inflexible, read some Tom Kurz and others and within a few months i was doing splits and high kicks. Now I barely stretch ever and still have it.
Powerlifting style low bar squats stress the hammies and adductors in a way that helps flexibility alot. Good mornings and RDL'is for the hammies.
stretch first thing in the morning. you will be unflexible as hell, but this will help alot.... ease into it. You need to spend alot of time initiaally stretching, 30min- 1 hour. Thankfully only for a few months.
As far as muscle relaxers, sounds fun. I take painkillers and do training sometimes and its awsome.