Okay, I'll start with some of my favorite links on the subject:
Tubarao's MLTR rules:
http://puarticles.blogspot.com/2008/01/ ... rules.html
BD on MLTR'S:
http://www.fastseduction.com/cgi-bin/se ... 1871591100
Now tell this girl that you just got out of a serious relationship and that you're really not looking to jump into anything super serious right now. Or just tell her that it's way, way too soon for you to consider being monogamous or serious with ANYBODY because your not the type of guy that just jumps into serious relationships.
Be prepared for shit tests. Hold strong.
It helps to sub-communicate that you are seeing other people: don't see her too often (once a week is ideal), don't do any boyfriend / girlfriend crap with her and don't meet her family. It doesn't hurt to leave scandalous items around your room: empty condom wrappers, sex toys, books about sex.. maybe a set of earrings or somebody's bra. Feel free to ask her, candidly, if she's gone on any other dates recently.. it shows that you assume she is (also) dating other people.
As for texting, don't text her very often. Only text to schedule meet-ups and work out logistics (when / where). Don't respond if she texts you inane things about her day. If she texts you direct questions, then only respond if you feel like it (don't feel obligated).
-Wolf