If you want the text WCU returned, use:
If WCU is the name of a field, remove the semi colon after it.
Case(WIP_list::gWharehouse="Custom" ; WCU )
Ah yes, thank you!
If I am using this result to perform a Find, and I want the Find to return results that match either of two values, how can I do that? I can make it work with a range of values right now, but luckily I have no other values in that range as of this date. For instance:
Enter Find mode 
Set FIeld [YourTable::Field ; first criteria goes here ]
Set FIeld [YourTable::Field ; second criteria goes here]
Set Error Capture [on] ---> keeps no records found error dialog from interrupting script when no records are found
Perform FInd 
Will find all records that meet the first or second criteria. Other methods, such as extend found set, can also be used to get the same results.
You may find this thread of scripted find examples useful: Scripted Find Examples