Yes. Noclip ? It's like typing sv_cheats 1 and then noclip in the halflife console, if you understand me.
Oh that....I have seen others do it, but I have not done it personally. The thing about the 3DXplorer.com 3D Java applet, is that it is basically a Java powered chat room, but in full 3D, that's all. It has no type of game engine built in to it, so no games can be played on it.
The only interactivity it has, is to move around with your 3D avatar, chat with others, play some embedded music or videos on the scene you might have and maybe activate some animated, moving objects, and that's it. So I don't think there is any equivalents of a Noclip for 3DXplorer's Java 3D Chat scenes, so no, sorry.
The only real, practical use this could have, is to maybe showcase some 3D models you might have made yourself in real time 3D in some "virtual showroom" of your creation. This way, anybody online can see them in actual 3D without downloading a browser plugin, gamer or non-gamer. This way, you can maximize the amount of people that can see your work.