To answer your question, you probably need a DAW (digital audio workstation) to edit the MIDI. There are a couple of methods you can try, neither one particularly easier than the other. One involves time-stretching the portion of the MIDI file that changes tempo and the other involves cutting the MIDI up into sections at those points where the beat changes, exporting from the DAW and then importing into different main drum loop sections in the BeatBuddy Manager (BBM).
Although you asked for a beat (I’m assuming that you wanted a multi-part song with just drums) most of the user-created content on the forum tends to be of the one-press variant. If all you need is a one-press drums (DOP) version, you can also find it at this link and the MIDI file was time-stretched.
P.S. Although the category you posted under was for the Aeros, I’m guessing that you really intended this to be posted under the BeatBuddy category and I’ve changed the category. If I’m wrong and you really intended it for the Aeros category, feel free to edit it.