My site, www.example.com has a MyBB forum installation, and has many users constantly checking it out. I would like to make a major change to it - basically, I want to delete everything it has and start clean.

However, this rebuilding process may take me hours since I need to do a lot of things. Thus, whenever an user tries to enter any part of my site (www.example.com, www.example.com/blog etc), the user will always be redirected to www.example.com/underconstruction so they can see a nice HTML site explaining the current situation.

But not only that - while I am configuring my site, I need to visit it myself to make sure things do work live. So basically, it has to redirect everyone who isn't me.

Is that possible in any way? I am using GoDaddy hosting.