Through Tobu to Kawagoe with metro pass?

If I have the 3 day metro pass sold to foreigners with the narita skyliner, can I take the through train to Kawagoe on Tobu, or do I physically have to take the Fukutoshin Metro and get off at Wakoshi and transfer to Tobu? Do I have to buy the supplemental before boarding a through Tobu train or can I pay excess before leaving Kawagoe Station?

can I take the through train to Kawagoe on Tobu

In that case, you have to make a fare adjustment, probably at a manned gate.
The one-way Tobu fare between Wakoshi and Kawagoe or Kawagoeshi is 310 yen.

Until Wakoshi Station, you can choose the Fukutoshin Line or the Yurakucho Line of Tokyo Metro.
A Metro-Tobu through train which runs via Kawagoe is destined to either Kawagoeshi or Shinrin-koen.
You can check a train's destination on a LED board.

On the way back, you purchase a Tobu 310-yen ticket, take a Tobu-Metro through train then show both your Tobu ticket and your subway pass (= Tokyo Subway Ticket) at a manned gate of your Tokyo Metro station.
Please note that Express and Commuter Express trains on the Fukutoshin Line skip some stations.

(Regarding the Tokyo subway network, the word "metro" refers to Tokyo Metro only, not also Toei subway; please use "subway" instead to prevent confusion.)

- japan-guide.com: How to get to Kawagoe
http://www.japan-guide.com/e/e6505.html

Enjoy your trip!

Thanks, very clear.