Using the alpha channel for a layer mask

I have a perfectly nice alpha channel that I'd like to use as a mask for one of my working layers.
I thought it would just be a case of selecting the channel, copying it, and pasting it into the mask, but that doesn't work.

I copied the alpha channel into a new layer, and change it into a clipping layer. This didn't work either.

I'm probably missing a very basic step. Can someone point me into the right direction?

Photoshop

- Ctrl + click the channel to load it as a selection (marching ants), then click the magical make layer mask button at the bottom of the layers palette.

- If you insist on using Copy and Paste, you will have to use a slightly obscure key combo. First, copy the channel you want to use as a layer mask. Now, in order to paste it directly into the layer mask, you will have to Alt + click the mask, then paste it in. What Alt + click Layer Mask does is show the 'raw' layer mask channel itself.

Alt + click Layer Mask to show the raw mask is a handy little trick that not very many people seem to know about. It's also very handy on occassion for hunting down artifacts and what-not in the mask.

I had a feeling it would be easy, lol! Thank you
I tried it both ways. I didn't know about the Alt+click Layer Mask. I can see that this little piece of information is going to become very useful.