I would love to get some help on this, unless you want to integrate mine into yours.
A quick introduction would make it easier for you to get up to speed:
I'm using objects heavily. Tried to strip it down to not using it, but it actually hurt performance instead of helping it. Not sure why that happened.
The library is currently working with 3 digits for each part, almost 10bits. This is currently only for laziness, but it sure should be easy to make it support up to 5 digits. I would like to make it bit-compatible, like you did, but due to how the library this was derived from was built, I think it would be hard to do such a thing without damaging the performance even further. It's not impossible, just hard. Would love to have this go up to 16bit.
There is a multiplication algorithm I added, but never tested. It's used when a certain criteria is met. Like if both numbers exceeds 1600 positions, which is extremely rare. I have no idea how fast it is, but apparently it is used only when big numbers are introduced. The sad part with that is that it heavily relies on objects.
Other than that, the divMod functionality I guess that you want to use for your own purpose. If you want, then go ahead, take it. It currently uses some objects already, but only to a certain extent.