LA doesn't serve IAH. You might be able to work some AA flights into the mix without completely killing the deal because LIM isn't so far away (using two or more partners triggers a distance based award chart, which is a deal breaker for flights to places like SIN, but not so much for regional stuff). That having been said, I have a hunch that getting yourself to a Lan gateway will probably be your best bet.

ETA: I just noticed that you want to fly AA (was thrown off my your Easter Island interest expressed previously). If that's the case, I suggest you perform an award search on aa.com first. In theory, BA should be able to fetch the same seats you can get there, though I wouldn't be shocked if AA held some inventory back for its own members.