I`m sure the personal scanners, will come to Argentina one day. Then you`ll just have to first find a scanner that still works. Have it chained to your person in case you steal it.
Go around the products scanning it, if they have barcodes, hopefully the scanner battery keeps going throughtout the duration of your shop otherwise you need to start all over again. Then you`ll get to where you pay ,a security guard takes all your shopping out of the trolley, inspects the items one by one to compare with the receipt. Checks your id, personal bags and then unchains the scanner and lets you leave.