Process of charging particles?

A person does not. A neutron with a (electric) charge is not a neutron.

Further, charge in general indicates sensitivity to electric or color conserved quantum numbers.

 

The particles can't be electircally charged, they have certain charges.
The particles can undergo certain interactions however, leading to changing their nature and charges. For example if you bombard neutrons with positrons, then you might achieve the process [inverse beta decay]:
[itex] e^+ + n \rightarrow p + \bar{\nu}_e [/itex]
If you call that "charging the neutron", then so be it. But I think this terminology is very bad. The neutron changes to something totally different.