To create a comments/instructions field to checkout page,
i.e. "Please include card with biscotti saying, Love David, etc."
BTW, there is a value gift_note that had been half-heartedly to the report page though I couldn't get it to work properly.
The files you'll need to add the comments/instructions value to:
Four files in /catalog_root/etc/report, mail_receipt, receipt, log_transaction adding:
"Comments: [value comments]" to the mail_receipt, receipt, report
and then adding:
"comments: [value filter=mac name=comments]"
to log_transaction so that it writes to the transaction table (if you want it to write to database):
Depending on the checkout process you use (multi-page or not):
I added this to /catalog_root/include/checkout/shipping_address:
There are a number of other pages that you will want to add "Comments: [value comments]" depending on your customization of IC.
I hope I'm not forgetting anything, though I probably am.