Tally HSN Code Updation

I need a little program for my business. All our inventory is maintained in Tally. Till now, we have stored the items with 4 digit HSN Codes in Tally. These 4 digit HSN Codes must be updated to 8 digit HSN Codes. We cannot do it manually because there are many parts to be updated. Therefore we need a program to read an excel, where in there is a part number and 8 digit HSN code. After reading it, the 8 digit HSN code must be updated against the part number.