Finally got around to using piklab-prog to program my surplus 16F84As. The command line options are a little confusing, so here is what I used:
piklab-prog -d 16F84A -t /dev/ttyS0 -p direct -h 'JDM classic' -c program led_test.hex
For some reason there is a hardware option which doesn't work for me and is not documented in the man page. piklab-prog seems to magically detect that I am using a JDM classic programmer, so all is well :-)
Cheers,
Steve