Finally, a solution to the annoying BLEEP and blinking LED when the battery gets low. Having a 3500 mAh on my Dx, with even 1% showing there is still several hours left, so once it hit below 20% the incessant nags would drive me nuts, especially when streaming audio/video, other tasks or at night. Not anymore.
First I installed Sound Manager v2 (tried others, failed) to stop the sound.- Turn system volume to desired level. Works well for managing ring/notification separately and other sounds too.
To stop the LED blinking, Light Flow did the trick! I tried several other apps (ex. Blink) and methods (change file name etc.) to no avail. I had to check the 'Direct mode' in General Settings for it to work on my DX and the 'Run in foreground' is checked as well. Next, under 'Low Battery', uncheck the 'Enable notification' and viola!, no more LED nag. Not sure about the pop-up, another inconvenience, but will find out. Since I already had Sound Master installed, I didn't try Light Flow by itself for the sound. It may do it all looking at all the options; I didn't test and wanted to pass this on while still fresh in my mind.
Hope this helps others even if a solution was posted long ago, but I sure couldn't find it.
Now if only there was a fix for the battery level using a big battery. Battery Left is "ok", but mostly just another little vampire novelty running in the background IMO.
BTW, having been a charter user since day one of Liberty, I'd like to thank the devs for Liberty 3. I still think the DX is the most versatile and customizable phone out there. My next phone must be capable of a BIG battery and long life. Nothing I've seen impresses much, so the DX will be around for a long time, knock on wood.