Currently: yes.
It's possible to add other custom lexers but that would require minor changes in wxscintilla source (adding dllexport for some classes), so currently it can not be done.
I work on some solution that would allow generating lexer for any language through custom C::B plugin (I was to tired of wxSmith so needed to code something different

) - that would give you ability to colourise the source just as you want by writing your own plugin, but for now it's just my personal experimental code so I don't know even if it will ever be included in the main sources (it requires some changes in sdk and wxScintilla).
Regards
BYO