The program runs on your computer and allows you to choose what you want displayed, instead of the dire warning message. Additionally, it will allow you to set the text in the pink bar above the S-ON/OFF status line.
RBC creates a flashable PJ75IMG.ZIP containing a modified hboot that you flash through the bootloader. As such, should you have a particularly awesome thing to say, or if you only have access to a PC at work, you can post your modified hboot for later/mass use.
The new tool is currently Windows-only at the moment and will require .NET 3.5 or above installed.
While any flashing comes with risk, flashing a modified hboot carries a lot more risk than any other form of flashing: if it doesn’t flash correctly, you can’t even get to recovery. So make sure you read up carefully, as changing a developer warning message into “HTC is a butt!” is not worth bricking your phone over.
[xda-developers]