actually: nope
you should not change a template with a product, because what would happen, if two products changes the same template?
exactly: a problem...
for template changes there should still be a install file, like the traditional one

(that may change with new versions of vb)
there is just one possibility you might have: manipulating the output of the print_output function, but as said, you shouldn't really do so, because if someone has a custom style, it won't work...