>I'm trying to create an updatable view. My base table has a compound primary key such as Field1 + Field2 + str(Field3,8,0) + Field4.
>I can't quite figure out the syntax for the dbsetprop() command to set the key field.

You don't have a single key field, but several. Therefore, judging from the documention, you should do

dbsetprop(Field1, "Field", "KeyField", .T.)
dbsetprop(Field2, "Field", "KeyField", .T.)
dbsetprop(Field3, "Field", "KeyField", .T.)