Not quite sure how to word this.

I prepare scripts for dubbing animation. There is a column beside the lines the actor reads where I enter the "timecode" of where the line begins. This corresponds to the video in the foreign language.

A typical timecode for example is 10:00:02:21 (hr:min:sec:frame)

I'm sick of entering colons beside every number, is there a way I can format the cells so that they would autofill the colons : between the numbers? So I could just hammer away on the numpad and not have to worry about them? Every code would be in that same format.

Sorry if this is a roundabout way to try and ask for something like this, I'm sure there's an easier way of expressing it.

Thanks!