Hi Benjamin Kirsch,
I think you can use parseDate,
var dateFormat = "yyyy-MM-dd HH:mm:ss";
var dateValue = parseDate("yourdatehere", dateFormat);
Yes, it works for a single variable.
For complete infotable; you will have to add one more column (type dateTime) in your ThingWorx infotable containing data retrieved from Windchill and then traverse through the infotable using for loop and do the conversion and update the Date/Time data in the new column.
Then you can remove the original String DateTime.
You will find the snippet/code for all these in the snippet section.
I hope it helps.