Ant Script ? to pad strings during build process? Other Script? Best way?

Experts:

I need to take .properties files with Key=value lists in them and pad the value (String) with characters to generate pseudo-localization (fake Languages) files during the build process.  I don't know anything about Ant.  Not sure if that is what I should be researching.  Looking for best solution.  Anybody out there know of a best solution?

To be more clear:

English version of .properties file:

BUTTON.Del=Delete
BUTTON.CONNECT=Connect To
BUTTON.CONNECT_TO=Connect to {0}
COL_HEAD.TYPE=Type
COL_HEAD.DIRECTION=Direction
SELECTONERADIO.WATTS=Watts
SELECTONERADIO.Amps=Amps
BUTTON.LOAD=Load
BUTTON.OK=OK
BUTTON.YES=Yes
BUTTON.NO=No

Italian pseudo-localization version of .properties file:

BUTTON.Del=à Deleteà
BUTTON.CONNECT=à éConnect Toà é
BUTTON.CONNECT_TO=à é Connect to {0}à é
COL_HEAD.TYPE=à Typeà
COL_HEAD.DIRECTION=à éDirectionà é
SELECTONERADIO.WATTS=à Wattsà
SELECTONERADIO.Amps=à Ampsà
BUTTON.LOAD=à Loadà
BUTTON.OK=àOKà
BUTTON.YES=àYesà
BUTTON.NO=àNoà

You will notice that the English version contains English string values. I need to read in each line, calculate the length of the string value, and pad non-English characters to the front and the back of the English string until the newly created string value is 50% longer than the original English string. This is how one creates pseudo-localization files for Internationalizing and testing an application. Therer are tools out there that will do this, however, they are manual intensive. I need to create a script to do this with the build. I know others have created these scripts, I just don't know what they used. Someone said that Ant PropertyFile can be used to concatinate strings to the values in a .properties file during the build process. But from the documentation I saw, the ability was a little primitive (like only adding the characters you specify). I need to resize the string to 50% longer. So, I'm looking for best way to do this.

Thank you in advance,
Patricia