I was able to add the Apex temperature probe to Homebridge by:
1. sudo npm install -g homebridge-temperature-cmd
2. adding the following to config.json
{
"accessory": "TemperatureCMD",
"name" : "Tank Temperature",
"command": "/usr/bin/curl --fail --silent --show-error --user <userId>:<pwd> http://<ip_address>:<port>/cgi-bin/status.xml | grep -i '<name>Temp</name> ' | grep '<value>' | cut -f4 -d'>'| cut -f1 -d ' '"
}
The homebridge-temperature-cmd package thinks all temps are in C, so assuming your apex is reporting in F you need to edit /usr/lib/node_modules/homebridge-temperature-cmd/index.js by adding the following line of code after line 40:
res = (res - 32)/1.8;
The Home app doesn't display the decimals but other HomeKit apps do.
Good luck!