I figured it out through trial and error and finding information on various websites. Try these steps, I'm using Visio 2003:
In Visio:
1. Create a Shape.
2. Add to the shape Custom Properties
[Hostname, IP Address, City]
3. Edit the custom properties through the shapesheet
prop.Hostname
prop.IPAddress
prop.LocCity
4. Save the object as a stencil.
In Excel:
5. On the first row of the sheet enter the following labels:
Cell A1 Hostname
B1 IP Address
C1 LocCity
6. Enter a few rows of information in the corresponding columns.
7. Save the Excel Spreadsheet.
In Visio:
8. Click Tools -> Add-ons -> Run Add-on.
9. Scroll until you find Import Data
10. The only option will be "Into Shapes that I manually Place", Click next. (Note: In the future, you only need to use this option as well when adding more shapes or updating information into shapes that already exist.)
11. Type is Excel, and the location of the Excel Spreadsheet you just created.
12. Select the Worksheet, in this case should be be Sheet 1. Include all rows and columns for now. Click Next.
13. Select the stencil you just created. Click Next.
14. Leave lable and color alone for you now and Click Next.
15. Unique ID is important, select something that is going to be unique to every object, like a hostname or ip address. When you import updates from the future, this is how it knows not to create a new object and to update the information already present on the drawing.
16. When you click next it will import all the information, creating new object for every row in the excel sheet.
That's it pretty much in a nut shell. There are other things you can do like pulling information from the Custom Properties into Text on the object so you don't have to do all the labeling and what not. Once I figure out the Macro, you edit the stencil to execute the macro on double click and should be able to telnet directly to the device. Just need to figure out how to get the custom property into the macro at this point...