I've written an abstraction layer for using Wire and SoftwareWire interchangeably: GitHub - pepaslabs/AnyWire: Arduino abstraction layer to support both Wire and SoftwareWire.
Included in the repo is a forked copy of HTU2xD_SHT2x_Si70xx which has been modified to use AnyWire, as well as a demo which reads from two SHT21 temperature sensors, one over hardware I2C and the other over software I2C.
Cheers!
