Convert JPG Comments to IPTC Keywords

I have a large quantity of JPG images that have been tagged in the JPG comment field. I need to move that data to the IPTC Keyword field. Different values are seperated by ;. I also need to be able to ignore the 1st and last value in the comment field. Lastly I need to ensure that image quality is not compromised and that date/time stamps of the photos is not changed. This process needs to be able to handle around 30,000 photos.