One option that I have experimented with, although I haven't put it in production, is prepending a pound sign to the incoming CallerID.  Because it is not a number, it is easy to interpret the digits correctly.  You just need to setup route plans that allow # as a PSTN access digit.  This will work with any version of CUCM, I beleive.  I don't know if there is a specific solution for this in CUCM 8.0.