you dont need a time signature option if you set the proper grid granularity and you deduce the correct mathematical fractions. Like I mentioned SAE wrenches are your guide to getting off time on a square grid. ignore that the grid has lines on the square part and program in on the piano roll until you figure it out.

Notice how all the wrenches are ending with 4,8,16,32? just like musical timing. the length of your loop shouldnt be distorted because of the spacing of your notes or else you will never have a properly formatted song in any sense just randomness and noise.
the first number is the number of notes evenly spread across the second number's amount of spaces. thats all. if you cant fit it, up the tc granularity (or denominator for those of you who remember math) to find the grid format that will fit the notes in the alloted spacing (numerator).
i may be misunderstanding what people want though.
Ego te absolvo.