alias ms.timestampfmt.fix {

var %timestampfmt = $timestampfmt

if ($regsub(%timestampfmt,<re>,$+(s.,$right($calc($ticks - %ms.timestampfmt.fix),3)),%timestampfmt)) { timestamp -f %timestampfmt }

}

Code:
\d{2}:\d{2}:\d{2}.\d{3}

this will match ##:##:##.###

but it sounds like you want
Code:
\w{2}:\w{2}:\w{2}.\d{3}

this will match !!:!!:!!.### where ! is anything a-z,A-Z,0-9

alternatively, you could have
Code:
[A-Z]:[a-z]:[a-z].\d{3}

this will only match AA:aa:aa.### where AA is upper, and aa are lower, letters only

I'm not sure what exactly you require, and there may be a better expression to use, I've never really played with regex before, but I did test these to confirm they match how I stated.

hope this helps,

HobophobE