relicensing from MIT to LGPL

[jmg3000]

I've come across an inactive software project that I'd like to
contribute to. I think the previous maintainer had pretty much written
the whole thing himself (save a few patches). This software is
currently distributed under the MIT license.

What steps must I follow to re-release it, with my changes and
additions, under the LGPL? (BTW, this topic might make a useful short
article on the FSF site's licensing page http://www.fsf.org/licensing
.)

My guess is that I leave the original copyright holder's name in every
file, with the date, and then put mine in below it:

Copyright (c) 2004 J. Random Hacker
Copyright (c) 2006 I.M. Newguy

(Though the original author sometimes didn't write anything more than
his name in the source code files.)

Regarding the MIT license notice, it says, "The above copyright notice
and this permission notice shall be included in all copies or
substantial portions of the Software.". So, do I put that, and then a
note about the LGPL above it? Do I put both notices in my "COPYING"
file?

Any tips welcome.

Thanks,
---John