i did it once for Verilog language. what i did was to look at other languages that i know as reference. you should know that the syntax to specify a language is very diverse, and some popular languages syntax files are very a complicated, so choose the minimum you need. also try and look if textmate has support for it, and maybe jon can help you convert it to sublime syntax.
over all it took me back then few hours to complete 3 languages simple syntax. any way good luck.