In reply to abs:
Look here, this is your starting point:
class parameterized_subscriber #(type my_obj = uvm_object, type T = uvm_sequence_item) extends uvm_subscriber #(T);
// omitted utils macros...
my_obj obj;
endclass
Now you can make atypedef like this (reducing to 1 parameter):
typedef parameterized_subscriber #(type my_obj = fixed_object, type T = uvm_sequence_item) my subscriber;
Where fixed object is an object you do not change in the subscriber.