Yes, it's possible. Unfortunately, unlike the vacation autoresponder which only sends the message once to the sender, you'll end up sending the message every time you receive a message.
First, you need to turn on the Canned Responses lab and set one up.
(To create a canned response, start by composing a new message, then in the context menu of the compose window choose
Canned responses > New canned response....)
Once you've got your canned response, now you need a filter.
Create a filter with the trigger
from:firstname.lastname@example.org and choose as the action
Send canned response: and choose the canned response you just created. You may want to make the filter more specific and/or choose other things to do with the message. (There are lots of posts here that cover Gmail and filters. Look under the gmail-filters tag.)
Now, whenever a message matches your criteria, a response with your canned text will be sent immediately back. As I mentioned, however, this will happen with every message that trips your filter.