Does not sound like a hard limit to me (if it is, tell him that...) since the context of the post implies:

1) She has done anal training before this point (and hence maybe why she knows she does not like it too much)
2) She is only looking for something to replace anal 'from time to time' i.e. she is aware that she is only going to be allowed to make the swap occasionally and therefore anal is still on the menu.

Like the above posters, I am not sure what you are looking for here exactly. Anal training is a very specific thing that makes you ready for anal sex by helping to relax the sphincter muscles using graded butt plugs and dildos. Not sure there is anything that could be an equivilent, though the oral training suggested sounds the closest...

If, however, it is *any* BDSM task that can replace it, I suggest something that is as unpleasant but in a 'different' way. Anal training is unpleasant because of the pain, discomfort and the constant feeling of needing to go poo. There is also humiliation. Find which of those you actually dislike and then find something which does not include it.

Some examples:

- position training or furniture training. Good for patience, general body tone and making a good view for your Master to look at when he is away on a trip and watching you on webcam. Can be very boring to hold the same position for ages though...

- Vaginal training. As anal training but using the vagina.

- Cum restriction or some other similar activity (i.e. practising not cumming while masturbating, maybe keeping a time log of how long it takes each time to send him in an excel file). In fact timing something (like position holding, length of time you can take certain pain such as kneeling on rice and so on) and sending the times to him in a spreadsheet so he can see a graph of your improvement/lack of improvement is a good thing to do as it gives you both a feeling of progress and achievement.

- Taking pictures of yourself 'presented' for him (positions, dressed sexy, using yourself as a table) and sending them to him. Maybe even doing video (in fact video is often easier cos you can set the video running and set yourself up while in shot then edit it later to remove the 'fumbling around with bits of rope bits'). Webcams often do recorded video or still photography these days.

Most of the above are mainly things you can do to keep him happy while he is away rather than replacements for anal training...