I was about to suggest putting a jam funnel in your teapot, and then I remembered that not everyone makes jam on a regular basis.

You could also use a regular funnel, I suppose. Although I feel I should point out that sciencey people LOVE funnels and use them for...strange purposes sometimes. (coughMEcoughcoughPROBABLY ALSO CONS_DETECTIVEcoughcough)

Also, as it turns out, you cannot brew looseleaf tea in a paper towel pouch.