greetings,
I'm new here, but I noticed no one else had gotten around to answering your question.
From my research, yes it is possible to bend using the tongue-block method. Most instructions claim the tongue-block method is more difficult than the lip-block/pucker method. For a breakdown of the different embouchures and their trade-offs consult:
[
www.musicianswebstore.com]
When trying to bend with any embouchure, good breath control is key. I found two pages that mention tongue-blocking while explaining bending:
[
www.musicianswebstore.com]
[
www.harmonicaclub.com]
I'm not sure if any of this helps you out or not. From lurking around the harp-tabs forums, other members often refer to Adam Gussow's youtube instructions as being helpful. you might want to try a search for "Adam Gussow" and "tongue blocking" (I don't use youtube, so I can't attest personally to Adam's instructional material).
good luck:-)