This is possible to use the recordset directly in the cart file like this but it is a little tricky to do.
You will need to create the recordset then move it into the specific rule that it is getting a value for. Once you move it into this rule you can specify a binding from the recordset, then before the end of the rule you must move the free result from the bottom of the page into this area.
The other thing you will need to do is replace the include to the connections file with the contents of the connection file.
I did a bit of testing on this to see if it were possible and how it could be done and this was the only way I was able to get it to work correctly. Keep in mind though that if you do it this way you will undo any changes you add to this file if you update the cart or any rules in it.