SQL to Domain Language - How?

I have been able to create numerous complex reports just by trial and error, but I'm now at an impasse. I only have domain access to create reports, so I cannot use basic SQL select statements.

I have a field called Load.TransportModeName and this field only contains 2 values ("LTL" and "TL"). I need an input parameter that asks the user to select one or both of these values.

Basically, what I need to accomplish is the equivalent of this (I think), but I need to do it at the query level:

SELECT * from Load where $X{IN,load.TransportModeName, param_TransitMode}

Would very much appreciate any assistance or guidance.