can i display a 404 to all users not of certain IP, display error to IP?

<!--     <customErrors mode="Off"/> -->
    <customErrors mode="On" defaultRedirect="~/404.aspx">
        <error statusCode="404" redirect="~/404.aspx"/>
    </customErrors>  
for my purposes of working with a live enviornment i've been moving the comments in the above code between the 'off' position and the '404' position. turning 404 off when i'm working so that i can see the errors generated, turning 404 back on when i'm done so that a nice 404 page shows for errors to users instead of my code-behind.
i was just wondering if there's an easier way to go about this? the best thing would be if i could have the 404 show to all users not matching a certain IP, so only my IP would see the errors, the rest of the world the 404. 
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