Interrupt Driven Serial Input using DT_Ints?

[circuitpro]

Can someone please point me to a link or example of how to make an interrupt-driven serial input buffer (hserin) for use with DT_Ints? I have had an interrupt jump to and receive an entire string of characters, but I've got too much going on for that, and will have to receive the string one character at a time, and put the command together when there's time. Any example would get me started. Thanks