Each switch can be modeled using its physical address. This is normal out of box configuration.
You can also model a Pingable model to represent the Virtual IP. However as this IP is shared between the two physical devices, this can cause unwanted DUPLICATE alarms.
To solve this, you can enter the virtual IP in the section of VNM settings for "Shared IPs." This should prevent the Pingable model you created from alarming on "Different mac but same IP"
NOTE: When you add the shared IP into the "Allowed Shared IP" box the IP does not immediately move to the "Currently Shared IP" box. Spectrum actually needs to see an issue with the IP first. Therefore your models need to be created and at least one occurrence of the alarm needs to occur. Once that happens and Spectrum detects an issue with the shared IP and asserts the alarm, then the IP moves to the "Currently Shared IP" box and future alarms will be prevented.
To monitor the Virtual IP up/down status separate from the physical switches, you can enable alarms on the Pingable (alarms on Pingables are disabled by default).
When using a Pingable to alarm, you need to set the Value_When_Red to "7." See this doc for reference: