Unfortunately, first beat marker only allows quadruple measure.
So there is no straightforward method.
If you allow partial (local) grid/bpm change, there is a technique to virtually achieve this.
For example, if you want to binary measure for a bar:
1. Go to the bar you want to partially change the measure.
2. Click [Make an adjustment from the current position] button to set partial(local) grid/BPM changing point.
3. Double the BPM value, simply because both 2-beats by original BPM and 4-beats by double BPM have the same time length.
4. Go to the next bar.
5. Click [Make an adjustment from the current position] button to set BPM changing point.
6. Halve the BPM to return to original BPM value, and now the bar is like as if it is a binary measure.
If you use this, take care to use beat sync function.