to make this code works with Holtek HT6P20 or HT6026
You need to check datasheets to see what needs to be changed. If handshakes/formulas are identical you would have a headstart, otherwise it is often better to start from scratch.
Tip: define the interface first, how do you want to instantiate the class, what parameters (pins?); how to read the wanted value? timing? formulas. ets
If you have a link to the datasheets please post them, allways informative 
Better make a new topic of this with a title that reflect the sensor type (get more focussed feedback)