Libtidy New Inline Tag

I'm using libtidy for C++, trying to get the contents of an attribute in 
a custom tag. Unfortunately tidyParseString() strips out this tag, is 
there a way to force it to leave it in or recognize it as an actual tag? 
I noticed that the htmltidy tool has the option to pass in 
new-inline-tags, but couldn't find anything in the library that allows 
for similar functionality. Is there an option I'm missing?

Thanks,
Murph