Rails: can I use polymorphic references with non-integer primary keys?

I have a database that uses UUIDs as primary keys, like this:

create_table "my_table", :id => false, :force => true do |t|
 t.string "id", :limit => 36
end

However, when I try to use :references for foreign keys to that table, it generates integer columns for the ID. Can :references be instructed to deal with a non-integer ID? My migration for the referring table is like this:

create_table "child_table" :id => false, :force => true do |t|
 t.string "id", :limit => 36
 t.references :my_table
end

I know that I could just manually create :my_table_id and :my_table_type columns, but I'm wondering whether :references can be made to do its magic under these circumstances so that I don't have to handle the id+type explicitly throughout my code.