Can I retroactively cost emp for prior period when he did not have a labor rate?

Hi there,

I have a group of employees who were given the wrong job (one that didn't have a labor rate set up in Projects' rate schedule).  The problem was discovered months later, long after periods were closed.  The fix going forward was that the employees were given their proper jobs and hence, labor rates.  But the long story short is that their time (that comes from OTL) when they didn't have a labor rate, shows as an exception due to Missing Cost Rate.  Is there any way I can go back and re-cost just labor for a subgroup of employees?