DL Lion to External then Clone

[tuni]

What I am thinking is to dl & install Lion onto the external drive first. I think my iMac would see the external in the Voyager dock ?

Then later copy or SD clone the folder from the external to the iMac .....

If I'm not making sense, please tell me how to set it up to do what I want:

I want to dl Lion but NOT install or place it on my iMac until I'm ready. I thought the best way to do this would be to do an initial dl/install onto an external. Then, copy or SD clone from the external to the iMac

??????