Well I sure don't know what you mean by "bypass IIS and redirect errors directly using IIRF".
IIRF is a URL Rewriter. It rewrites or redirects URL requests. It does this by intercepting incoming requests.
If IIS detects an error and sends an error response to the requester, that happens *after* the request has been received by IIS and processed. Well after IIRF has had the chance to rewrite or redirect.
So, no, I don't think IIRF can do what you are imagining.