Special thanks to Chet, who provided me with the info:

Manually Building Network Topology

You may want to manually build your network topology when you are unable to have Zenoss automatically model all of the hops between your Zenoss server and the devices you're monitoring. For this example I will be monitoring www.zenoss.com over the Internet through my Cox cable modem. We will assume that www.zenoss.com (72.51.42.180) sits on a /24 network

1. Create a device class to hold our intermediate routers that we can't model
     a. Create the /Networks/Router/Unmanaged device class
     b. Edit the zProperties for this device class
          1. Remove all plugins from zCollectorPlugins
          2. Set zSnmpMonitorIgnore to True
     c. Go the the Templates tab for this device class
          1. Add a template called Device
          2. Leave this template blank

2. Run a traceroute from my Zenoss server to www.zenoss.com to see what the hops are.

     chet:~ chet$ traceroute www.zenoss.com
     traceroute to comm1.zenoss.com (72.51.42.180), 64 hops max, 40 byte packets
      1  10.0.4.1 (10.0.4.1)  1.491 ms  1.144 ms  1.174 ms
      2  ip68-100-28-1.dc.dc.cox.net (68.100.28.1)  10.909 ms  10.571 ms  12.645 ms
      3  ip68-100-1-161.dc.dc.cox.net (68.100.1.161)  9.616 ms  13.981 ms  10.867 ms
      4  ip68-100-0-1.dc.dc.cox.net (68.100.0.1)  10.228 ms  17.619 ms  10.406 ms
      5  mrfddsrj01-ge110.rd.dc.cox.net (68.100.0.161)  13.269 ms  11.424 ms  10.036 ms
      6  dalsbbrj01-so100.r2.dl.cox.net (68.1.1.220)  44.545 ms  43.887 ms  48.915 ms
      7  oc48-po10-0.la-600w-cor-2.peer1.net (216.187.124.121)  109.927 ms  112.757 ms  106.192 ms
      8  oc48-po4-0.la-sb600w-dis-2.peer1.net (216.187.88.150)  104.864 ms  104.346 ms  107.006 ms
      9  comm1.zenoss.com (72.51.42.180)  105.982 ms  104.439 ms  128.912 ms

3. Add a device for hop #1
     a. Go to Add Device
     b. Enter the IP address of the hop
     c. Select /Network/Router/Unmanaged as the Device Class Path
     d. Select "none" as the Discovery Protocol
     e. Click Add Device

4. Create a fake interface for the new router
     a. Go to the new router's OS tab and add an interface called fake0
     b. Set the Type to Other
     c. Set Monitor to False
     
5. Create a route to your destination network
     a. Go to the new router's OS tab and add a route
     b. Set the Destination to 72.51.42.180/24
     c. Set the Next Hop to the next hop (68.100.1.161)
     d. Set the Protocol to local
     e. Set the Type to indirect

6. Repeat steps 3-5 until you reach the last router (second to last hop)

7. Repeat steps 3-5b on the last router then take the following additional steps
     5c. Set the Next Hop to 0.0.0.0
     5d. Set the Protocol to local
     5e. Set the Type to direct