SciTE properties for GNU assembler MSP430 source syntax highlighting. Copy the content to .SciTEUser.properties and modify to your liking.

.SciTEUser.properties

# Show .s and .S asm sources in file open dialog
source.files=*.asm;*.c;*.cc;*.cpp;*.cxx;*.cs;*.h;*.hh;*.hxx;*.hpp;\
*.rc;*.rc2;*.def;*.java;*.js;*.py;*.pl;*.rb;*.cgi;*.lua;*.conf;\
Make*;make*;*.mak;*.properties;*.html;*.xml;*.iface;*.bat;\
*.s;*.S;*.dump;*.haml

# GNU asm file
file.patterns.gasm=*.s;*.S;*.dump
filter.gasm=GNU Assembler (asm)|$(file.patterns.gasm)|
lexer.$(file.patterns.gasm)=asm

# GNU asm directives
directive_gas=.abort .align .ascii .asciz .balign[wl] .byte .comm .data .def \
  .dim .double .eject .else .end .elseif .endef .endfunc .endif .endm .endr \
  .equ .equiv .err .even .exitm .extern .fail .file .fill .float .func .global \
  .hword .ident .if .include .incbin .int .irp .irpc .lcomm .lflags .line .ln \
  .list .long .macro .mri .nolist .octa .org .p2align[wl] .print .psize \
  .purgem .quad .rept .sbttl .scl .section .set .short .single .size .sleb128 \
  .skip .space .stabd .stabn .stabs .string .struct .tag .text .title .type \
  .uleb128 .val .vtable_entry .word 

# MSP430 registers, instructions and byte/word instruction variants
gas_r_msp430=r0 r1 r2 r3 r4 r5 r6 r7 r8 r9 r10 r11 r12 13 r14 r15
gas_i_msp430=adc add addc and bic bis bit br call clr clrc clrn clrz \
  cmp dadc dadd dec decd dint eint inc incd inv jc jhs \
  jeq jz jge jl jmp jn jnc jlo jne jnz mov nop pop push \
  ret reti rla rlc rra rrc sbc setc setn setz sub subc \
  swpb sxt tst xor
gas_ib_msp430=adc.b add.b addc.b and.b bic.b bis.b bit.b \
  clr.b cmp.b dadc.b dadd.b dec.b decd.b inc.b incd.b inv.b \
  mov.b rla.b rlc.b rra.b rrc.b sub.b subc.b tst.b xor.b
gas_iw_msp430=adc.w add.w addc.w and.w bic.w bis.w bit.w \
  clr.w cmp.w dadc.w dadd.w dec.w decd.w inc.w incd.w inv.w \
  mov.w rla.w rlc.w rra.w rrc.w sub.w subc.w tst.w xor.w

keywords.$(file.patterns.gasm)=$(gas_i_msp430) \
  $(gas_ib_msp430) $(gas_iw_msp430) 
keywords3.$(file.patterns.gasm)=$(gas_r_msp430)
keywords4.$(file.patterns.gasm)=$(directive_gas)

# Dont know how to compose GCC arguments, so lets just use make
command.compile.$(file.patterns.gasm)=make