Robert,

in this case use of two Hserin can work. You'll need 1 extra i/o to confirm to pc to send next character.

By example, if you plan to download an EEPROM dump from your PC to your PIC and then dump it to an external eeprom, you need some time to get character, place in var, send to external eeprom, wait the appropriate delay time required by your EEPROM, and wait for the next character.

Easier with SERIN2 that handle everything for you and provide this extra 'flow control' pin.