You should be able to use the hub to connect your keyboard and wireless mouse dongle thingy into one USB port on Masso ( the port with the keyboard symbol ) and then plug your thumb drive with programs directly into the other USB port. G2 has two USB ports and G3 I believe has four.
I've just had a quick look in the MASSO documentation but can't find it, but somewhere in there it says that all software & code can be loaded onto the same USB stick and inserted into the "top" USB port.
PS. I'm using a powered USB2.0 hub with no problems.
Part of the software install is file extension renaming. When the new software has been installed the HTG extension is changed to HT1 for the serial number file, so the install firmware ignores the software update on the USB stick. I remove it from the USB stick after the update to regain memory space from my code files. But lately I gone to using one USB stick for code and another for Software, copying the update into a folder with the version name, so I can backup if things go wrong. Especially as I'm an alpha tester.