TiVo recently launched a mobile site that works well on Windows Mobile browsers.
If you have a TiVo you should check this out. It works pretty well unless you have multiple TiVo units. If you do, it asks you to pick one when you log in and that becomes the default unit you can program. There doesn't seem to be an easy way to change to a different unit. That can be a problem if you schedule a show on unit 1 and it is blocked because another show is already scheduled and you'd like to try again on unit 2. I am not sure why they cannot provide a basic dropdown to select the unit you want to program like they have on the full site.