Redirect 302 from portal HTML page possible?

[nemesisdev]

I'm hosting the captive page code on a different host.
Right now the redirect is being done with HTML meta refresh tag, however, I wonder if it's possible to send HTTP 302 header instead? Last time I tried this wasn't working, probably header section is already closed by the time this code is included, I wonder if there is another way or if there's any other information I am missing on this topic.

Thanks in advance!