Using Scan From String.vi you should be able to separate the desired components of your initial string.
I add a simple vi that parses your example header into three fields: return value, function name and parameters. Be careful: in the last item of the format string, a space is added in order to extract all the parameteres string, otherwise only the first 'const' will be extracted.
This last item must be modified in case of a function with more than one parameter: add a comma in the format string of Scan From String.vi in order to extract all parameters in a single output string, and scan from this one extracting characters in set [ A-Za-z], so dividing tokens when a comma is encountered.
Hope this helps
Roberto