You seem to be familiar with the concept of a conditional value list. In most circumstances the user wants to choose the condition that the list is based on. You don't - so just use the same principle of getting the value list through a relationship (usually based on the user's choice) but replace the 'user's choice field' with a permanent 'hard-coded' component in the relationship. Like:
Employees::ConstantFullTime = Employees::Status
Or you can not use a relationship at all.
Define a calculation field that returns the value you want in your list only if the Employee is "full-time" and is empty otherwise. Then set up your value list to draw values from this field.
Say you have a value list that lists EmployeeID as the primary field and EmployeeFullName as the secondary field.
Then set up your value list to draw values from a calculation with this expression:
If ( employeeStatus = "Full-Time" ; EmployeeID )
Instead of from the EmployeeID field. You can still specify the EmployeeFullName field as teh secondary field.