Dave,you might consider using the thermal expansion coefficient (alpha*dT) in the T2 field. CAESAR takes this number and multiplies by the element length to calculate the thermal growth (negative or positive).
This may require that you adjust the default "alpha tolerance" in the Config/Setup dialog. See Technical Reference Manual pages 2-4 and 3-9 for more info.
An alternate solution may be to edit the materials database (although I don't think this is the preferred method).