WARNING: Do not wipe, as this is using your cached prior HtcClockWidget.apk signature verification. Which means you should have the stock widget active on your homescreen before you flash this. This is tricking the clock into thinking the .apk is signed correctly.. It is highly advised you nandroid backup!! If you wipe your cache for any reason you will lose the clock and possibly cause other errors. If you need to wipe for some reason, delete HtcClockWidget.apk in system/app via Root Explorer or ADB.
The HTC Clock Widget MUST be actively open on your home screen.
You can NOT move it.
You can NOT remove it from your home screen and add it again later.
You can NOT look at the different clocks the widget has to offer.
Long story short, make sure the clock is on your home screen before installing. Do NOT touch the clock other than to open the weather.