[X4U] How to SSH and report a system sample?

[Michael Elliott]

I know that there are some great Terminal jockeys out there, but I'm  
definitely a GUI kind of guy.

I reported a bug to Apple via http://bugreport.apple.com  and they've  
asked for more information.  Since this is an intermittent freeze  
(one app will go Beachball, then multiple others eventually follow,  
and I'm unable to log out or select menu items), they've asked me if I'm

  "able to SSH into the machine that is hung and capture a sample of  
the system while it's in the hung state"

I can SSH into my iMac via

SSH imac.local     and run top, etc.

But then I have no idea how to "capture a sample of the system".

Can someone give a neophyte some succinct instructions on how to do  
this?

Thanks!

Michael