This is a very quick and dirty KDE KWrite/KATE highlighing file for BeebASM. I can do a much better job of this later - I should parse the commands more intelligently so I can pick up things like the A in LSR A. As it is I'm not changing context at all, which is massively lazy.

To inflict it on everyone put it in:
/usr/share/kde4/apps/katepart/syntax/

To keep it to yourself put it in (you'll probably have to create this folder)
~/.kde/share/apps/katepart/syntax/

You'll have to go to Tools->Highlighting->Assembler and select BeebASM 6502 in Kate as there is already a standard 6502 highlighting file that does curious things such as using $ for hexadecimal numbers.

EDIT: To choose BeebASM6502 highlighting in KWrite you need to go to Settings -> Configure Editor -> Enable power user mode and follow the instructios for KATE.