Insert Dash when the code has 4 digits or 4 letters in a row

[macfan55]

I have another question about the insert of a dash-sign (-) in a code of 7 characters.

 

That is if there is a way to search for 4 digits or for letters in a row (could be any digits or letters) and when so to separate them in 2 parts of two with a dash in between.

 

Examples of such codes to be changed:

 

12-ABCD changed into 12-AB-CD

ABCD-12 changed into AB-CD-12

1234-AB changed into 12-34-AB

AB-1234 changed into AB-12-34

 

Help will be much appreciated!