You can use something like this to set the value of a check box ...
This will set Q1 code 10 to a "1" (as if you checked the check box).
This script can be placed into the footer of a question after Q1 has been answered. Make sure you are careful that the question you place it on is not skipped.
You can also apply Perl to this script if conditions apply.
Or are you referring to recoding as per the examples below ...
Q1_4 to Q1_98
Q1_5 to Q1_99
This can be done within the Data Management menu option.
Go to File | Data Management and then select the Export Data tab. Select your Job Name and then click Edit Selected Job. Click on the Recode button. Here you can add a recode definition. In this area you can recode your questions, lists and even other specify and exclusive codes like "None of the above".
Is this what you were after?