Here you go... I think this has the info that you need. I got it from
http://www.s10forum.com/forum/showthread.php?s=&threadid=5155 - Instructions originally from Tha_Boom.
** Theftlock Bypass
1. Press and hold presets 2 & 3 for about 10 seconds until the first 3 digits of the display code are displayed.
2. Write the numbers down.
3. Press the AM/FM button, write down the next 3 numbers.
4. Call 1-800-537-5140, when asked, enter 202107, press the # button and enter the 6 digit code from the radio, you will get an unlock code, write it down.
5. Go back to the car, press the HR button and set the first 2 numbers, then press minute button and set the next two last numbers, press AM/FM button, SEC should be displayed, turn on radio.
To remove codes, repeat step 5. you should see --- on radio face, the code is now out of the radio.
you might have to use diffrent buttons to acomplish this depending on your radio. also if you skrew up the code 3 times you will have to leave it powered up for 1 hour for it to reset. **
I hope this is what you needed.
DogP