Sent you a PM. Hope it helps. A guy shared his guide on OPO forum and I did it, so far so good. Since I'm not good at rooting device, I'm not sure about flashing custom recovery thingy. But the main thing I root is because I want to use betterbatterystats app, and I didn't want to reset my phone, so the guide helped me out.
Edit: it seems Tapatalk allowed the PM to be sent but in fact it is not there.
Edit 2: search for member JuanLitvin on OPO forum and you will see his thread with the title:
Root Guide (OnePlus One) - Doesn´t wipe your data!