talk dirty to him. Then hint that you want him to talk dirty to you too. As you say, it is hard to make sure it doesnt sound cheesy. Maybe find out what HE thinks is he best physical feature, and talk about that, thats how i would go about it. BTW i really like your sig pic.
I've always been horrible at talking dirty and initiating... As a guy, these are normally the skills expected of me, but I'm more into tough chicks that smack me around and do the talking. He might have a similar mind set, or another one that acts as a mental block for dirty talking. BFTrick, PWN that devilfish hammerhead sky ray whattever the fuck it is I hate those gay squishy tau.
As long as he is not one of those guys who're rarely in the mood, it wouldn't sound corny coming from you. (I second that. LOVE your sig pic)
The solution to your problem is a simple one. The best way to open up those lines of communication is to say something dirty while you two are having a normal conversation. It doesn't have to be anything too dirty. For example, the next time you guys are out to eat and having a normal conversation about whatever, throw in "I really like to get fucked from behind". He might be thrown off by how direct you are, and not know how to react at first, so wait a couple of seconds and then say "What about you? Do you like to fuck me from behind?" If he says yes, ask him "Why?" He may not know what to say at that exact moment, or he might say something corny and stupid. That's ok. The point of this exercise is to get him learn how to put his feelings, desires, and fantasies into words, so that he can present them to you in a very sexual, dirty, nontechnical fashion. It's kind of like getting in front of a crowd and giving a speech. The first time you are nervous and probably suck. But the more you do it, the more comfortable you are with it, the easier it becomes, and the better you get at it. Good luck.