Perhaps, if you have stuff on your LAN already in the same file directory
structure as the online version. You can try these steps:
1. Start a new project and begin mirroring. Stop after a few minutes.
2. WinHTTrack should already have set up the base structure of the mirrored
website
3. Copy what you have inside the folder which should be named the URL of your
website/desired captured website (e.g.: somemysite.com)

ALSO: If your webpages have absolute links to files/other pages, this probably
won't work. However if they have relative URL links to other files/other pages
it should be fine. 
(Absolute - full url to a file
Relative - path of a file relative to current webpage)