Countdown Timer BB Code [Completed]

[akz645]

https://vborg.vbsupport.ru/showthread.php?t=171690 -> vB3
Anybody know how to make it work for vB4.2.3?

Basically, allow members to use a BB code to do a real time countdown.
Although I'd prefer if somebody knew how to code it differently (what I wrote below).

A countdown that indicates how many Days:Hours:Minutes:Seconds remaining.

^Displaying exactly like that, while having it countdown live would be great.

As for what Users have to do:
00:00:00:00 = DD:HH:MM:SS = Days:Hours:Minutes:Seconds
Example: [COUNTDOWN]00:12:03:31[/COUNTDOWN]
Note: Users should only be allowed to enter numbers otherwise it's invalid
& they shouldn't be allowed to use:
24-99 for hours (invalid)
OR
60-99 for minutes (invalid)
OR
60-99 for seconds (invalid).