I don't know the character sets you have.Maybe ( if they are uppersets) you could change them to WE8ISO8859P1.
That works on mine in 8i ...bonne chance :


SQL> CREATE TABLE test (
2 t1 INTEGER PRIMARY KEY,
3 t2 VARCHAR2(10)
4 );

Table créée.

SQL>
SQL> INSERT INTO test VALUES(1,'français');

1 ligne créée.

SQL> select * from test;

T1 T2
---------- ----------
1 français

SQL> select * from nls_database_parameters;

PARAMETER VALUE
------------------------------ ---------------------------------------
NLS_LANGUAGE AMERICAN
NLS_TERRITORY AMERICA
NLS_CURRENCY $
NLS_ISO_CURRENCY AMERICA
NLS_NUMERIC_CHARACTERS .,
NLS_CHARACTERSET WE8ISO8859P1
NLS_CALENDAR GREGORIAN
NLS_DATE_FORMAT DD-MON-RR
NLS_DATE_LANGUAGE AMERICAN
NLS_SORT BINARY
NLS_TIME_FORMAT HH.MI.SSXFF AM

PARAMETER VALUE
------------------------------ ---------------------------------------
NLS_TIMESTAMP_FORMAT DD-MON-RR HH.MI.SSXFF AM
NLS_TIME_TZ_FORMAT HH.MI.SSXFF AM TZH:TZM
NLS_TIMESTAMP_TZ_FORMAT DD-MON-RR HH.MI.SSXFF AM TZH:TZM
NLS_DUAL_CURRENCY $
NLS_COMP BINARY
NLS_NCHAR_CHARACTERSET WE8ISO8859P1
NLS_RDBMS_VERSION 8.1.7.0.0

18 ligne(s) sélectionnée(s).

SQL> select * from v$version
2 ;

BANNER
----------------------------------------------------------------
Oracle8i Release 8.1.7.0.0 - Production
PL/SQL Release 8.1.7.0.0 - Production
CORE 8.1.7.0.0 Production
TNS for 32-bit Windows: Version 8.1.7.0.0 - Production
NLSRTL Version 3.4.1.0.0 - Production