I think what the original poster want is to use the DBMS_SUPPORT package functions, this way :

sys@prod::SQL>desc dbms_support.start_trace_in_session
PROCEDURE dbms_support.start_trace_in_session
Argument Name Type In/Out Default?
------------------------------ ----------------------- ------ --------
SID NUMBER IN
SERIAL NUMBER IN
WAITS BOOLEAN IN DEFAULT
BINDS BOOLEAN IN DEFAULT
sys@prod::SQL>

See, in Oracle 7.3.4 (but not in all platforms) Oracle give to you a script to build the DBMS_SUPPORT package (useful to trace session with waits info and bind vars without oradebug, and without the PID).
In 8.X the script is gone, but it can be requisited from Oracle, or you can use the same version present in 7.3.4 database - I did it with 8i and 8.0.x).

Regards,

Chiappa