So, you have a small LCD character display, with a Hitachi HD44780 compatible controller and a PIC. You want to control the LCD display from the PIC. There seems to be quite a bit of sample code on the web, however, it seems to either have been written or an alternative microcontroller or in assembly. Well, here's a very basic library for writing to the controller from SDCC.
SDCC, the Small Device C Compiler, is an open source C compiler for a number of microcontrollers and small platforms. This document describes how to get SDCC installed and working under Linux, provides an example code and a description of how to compile it for the 16f877, 16f84 and 18f252.