This will not be possible. The javascript embed code is meant to run on an external site, not on a Discourse site.
I think that for most cases, having discussions about wiki topics take place in the topic’s replies section is useful. A general rule is that if someone knows that the wiki needs to be updated, they should make the change directly to the wiki topic. If someone has questions about the topic, they should reply to the topic with their question. The answer to the users question should then be incorporated into the wiki if it is useful. Questions and their replies should be deleted once the information has been incorporated into the wiki. Questions that are irrelevant to the topic should also be deleted.
That type of approach will keep your wiki topics up-to-date. Deleting questions/replies as issues are resolved will keep the topic’s discussion readable.