I posted a question from another deve's computer so I did not login to SO. Now I need to edit and\or comment on an answer.
Is there a way to do this?
As long ask you have 50 rep, you don't need to be the question author to comment. Being the question author doesn't give you any special ability to edit answers, either (you still need 2k rep).
You ought to have the accounts merged so that you can accept a correct answer when you receive one, however. Email firstname.lastname@example.org and ask them to merge your account with your anonymous account. Note that you might have to edit your profile on the other dev's computer to prove that the other account is yours.