No, I did not say hexadecimal, but octal.
http://en.wikipedia.org/wiki/Octal
Ok, this is one way to go, but needs to do it by two filtered steps.
Another way to go would be to modify the tag-field TRACK, after importing the number string having the leading zero, by an action "Format value" using the format string: $num(%TRACK%,1).
DD.20120120.1444.CET