i'm looking for advice and help from anyone with more experience than me here (which is probably almost everyone). i've never done any kind of anal play - not butt plugs, not beads, nothing in my asshole at all.

my Almost-Master has stated that He would like to sodomize me. It is not so much a sexual thing, as something that He would like to make into a part of my submission. Here is what He wrote to me about it:

I consider it to be an important aspect of submission for you to receive it at some time. Not "essential", but "important". To most subs, submission to sodomy is either more difficult than submission to whip or bondage (making it a good "goal" in its own right) or no big deal (in which case, it's simply something I get to enjoy

I typically treat the sodomizing of a sub as an act of domination, and do not go out of my way to make it a pleasurable act (as one would typically define an attempt at "anal sex"). It is something you would be doing to prove your loyalty and submission. Nor do I go out of my way to make it unduly painful, I would treat it as our other activities, with continual reassurance in touch and words...
i don't think that this is a hard "no way" limit for me. Right now, it's on my "things i need more time to work up to" list with Him. But i would be really interested for any advice or suggestions from people here who have done and enjoyed this.

Oh, one caveat ... He has said that the very first thing that He wants in my ass is Himself. So my rules won't let me start off with beads, toys, etc. Still, any advice - even reassurance that it won't be as bad as i'm imagining the pain to be - would be extremely welcome.