Signing a document with my SSH key, not a PGP key?

[Kelly Jones]

I want to sign a document with ~/.ssh/id_dsa so that people who have
my public SSH key (~/.ssh/id_dsa.pub) can confirm that it's from me. I
don't want to encrypt the document, just sign it.

How can I do this? Is it a good idea? Does ssh-keysign (which is
disabled by default) play into it?

I know how to sign things using a PGP key, but was wondering if an SSH
key would work as well?

-- 
We're just a Bunch Of Regular Guys, a collective group that's trying
to understand and assimilate technology. We feel that resistance to
new ideas and technology is unwise and ultimately futile.