In 8.1 (release later this fall) you will be able to write an R script to do this. In fact there's a recent blog post somewhere that does exactly this. If I find it, I'll post it here. There are also batch geocoding utilities the can take addresses and automatically return lat/longs for you, rather than doing them one at a time by hand. Here's the one I use: Batch Geocoding
Here's the post: Data Science Group. I think the R geocoding might be useful to help build out a database of local data, but it's not a good long-term solution because of the limitations noted in the post (limited to 2500 records, 1-3 records per second, every refresh of the view re-geocodes the data).
You may be able to replace the Custom Geocoding with a simple live connection to your geocoding data source, and bring your live geocoding lat/lon data into your visualization by using Data Blending.