Back in 1995, I wrote a PC-based bootloader for loading S19 records into most 68hc11 variants. The program was written in Microsoft C and uses a COM port to talk to the target. I'm providing both the source file (bootload.c) and the executable (bootload.exe). The source file needs no extra .h files other than those already available in the Microsoft set.
Warning: The source code is not very well commented; sorry about that.
bootld11.zip (19K) Source and executable for a PC-based 68hc11 bootloader. Uses serial port (selectable), supports many 68hc11 variants.