If you are merely attaching the hard disk to another computer, and booting from the other computer, there's no risk to the other computer. The other computer doesn't need to be in safe mode, or command line-only mode. You can easily recover files.
That is, there is no danger if autoplay is disabled. But, autoplay should be disabled on any computer anyway. It's an enormous security hole that Microsoft introduced to the world in 1995 and should never have seen the light of day. (The most reliable way to totally disable autoplay is in group policy. As for "easier" ways to do it, sorry, Google it--I don't keep track of how Microsoft modifies autoplay behavior each week to suit their whims of fancy.)