How to charge to 4.1 volts is here under settings

https://www.progressiverc.com/media/iCharger%20106B+%20Manual.pdf

In very short form, find settings using the buttons and scroll to lipo termination voltage.  If you hold the R button down, the voltage will blink and then you can increase or decrease. 

Whether to terminate charge at 4.1 volts is another matter.  The question will be whether you have enough capacity to charge to only about 4.1 and then fly a full flight and not go below 20%.  Going to low can harm the battery and shorten life.

Some higher end chargers( like the iCharger) let you adjust the termination voltage, but many others don't.
With almost all "4 button" chargers you can get 4.1 volt termination by selecting LiIon as the battery type.
Charge method is the same (Constant current then constant voltage) for all lithium types.

Pat MacKenzie