Thread moved to Server forum.
This may be a display of total ignorance on my part, but the one way I sort of know to do that would be to put a .htaccess file inside the folder you don't want people to see, and insert code something like this:
ErrorDocument 403 <font color='"#0000CD"'>/redirect-folder/</font>
Deny from all
Allow from <font color='"#FF0000"'>111.222.333.444</font>
/redirect-folder/ would be the folder you redirect everyone to, and the bit in red is your own IP address.
This is not my area, though, so I may get shot down for this! But I can take it. I'm happy to learn. This will only suit you if the page you don't want people to see is in a folder of its own, too. I'm sure there will be other solutions if you need something else. Maybe even PHP would be the way to go.