Best way is to use Excel and a DDE function to/from RSLinx (search this site there are several examples). Then you setup a column of addresses and the value next to it and do a DDE write.
Another simpler way is to use an Excel macro to use SendKeys function and write it online. I use that for PLC's where the comments are stored in the PLC to write new comment while online in run mode.
There is also sample code on the AB site to read/write values to/from the SIM card, but it's very complicated code.