The patch generated with tp_smapi's make patch does give errors on the 2.6.23.8 kernel.
ERROR: "thinkpad_ec_try_lock" [drivers/hwmon/hdaps.ko] undefined!
ERROR: "thinkpad_ec_invalidate" [drivers/hwmon/hdaps.ko] undefined!
ERROR: "thinkpad_ec_unlock" [drivers/hwmon/hdaps.ko] undefined!
ERROR: "thinkpad_ec_lock" [drivers/hwmon/hdaps.ko] undefined!
ERROR: "thinkpad_ec_prefetch_row" [drivers/hwmon/hdaps.ko] undefined!
ERROR: "thinkpad_ec_try_read_row" [drivers/hwmon/hdaps.ko] undefined!
ERROR: "thinkpad_ec_read_row" [drivers/hwmon/hdaps.ko] undefined!
make[1]: *** [__modpost] Error 1
Logged In: YES
user_id=1396959
Originator: NO
Please retry with tp_smapi 0.33.