You cannot directly convert CR to LA. I mean, if that were the case, then a level 10 Dwarven Warrior would have an LA of +10. Or something. They are not connected in any way, except that both go up as the creature is more powerful. The reason for this is, as Nyte said, that some monsters have abilities that are better for players than for monsters, and vice verse. And sometimes a creature will not have an LA because it's not meant to be played by a player (or can't). This is the case with animals, oozes, most undead, etc. So you have to ask the DM. Work with your DM to see what an acceptable LA would be. I'd say at least a +2 with a racial HD, or at least a +3. I don't know what the abilities are (and don't feel like opening my book), so I can't be of more help. Do keep in mind that LA follows a bit of a logarithmic power increase. This is to say that a +1 LA is not much of a cost, but a +2 is a pretty big cost, and a +3 is almost prohibitive, while a +4 is just insane.