So I was able to get this to work using Tasker and Maker API. Some high level notes are below on how I set it up:
Select Your Device
Decide how you want to interact with HE, I will use the example of turning a switch device on. Locate the device to be used in the HE Web UI, accessing the Device Edit page and noting the Device Id in the URL. If not using a switch, identify the command you wish to invoke before the alarm goes off by looking through the commands at the top of the Device Edit page, including noting any parameters required by the command.
Install Maker API
To setup Maker API, navigate to the Apps page in the HE Web UI, choose to install a Built-In app, select Maker API. In the install page adjust the app name if you prefer, select your devices to expose (I would suggest only selecting those you intend to use, you can come back and adjust this list later). Adjust any other settings as you wish. Copy the second last URL provided, an example of a Send Command URL. Click "Done" to install the Maker API App.
Test the Maker API setup by taking the Send Command URL, replacing the Device Id text with the Id of the device being used, replace the command text with that of the command being run, e.g. "on". If there are no parameters, remove the secondary parameter text. Paste the resulting URL into a browser address bar and run the URL. Confirm the command is run through HE or observing it in the real world
Setup a profile in Tasker triggered by a change to an alarm on the phone / tablet
The actions for this profile are to set the "minutes before" variable and another variable to store the time HE will be triggered in seconds, see the video I linked in my previous post.
Setup a second profile triggered at the time calculated in the first profile, again see the video for setting up this trigger. The action for this profile is a HTTP Request with a URL setting of the command URL copied during the Maker API setup, inserting the Device Id and, if using a switch, entering the text "on" (no capital o) and removing the placeholder for the parameter. As an example, minus some detail:
http:// Hub-IP /apps/api/2084/devices/419/on?access_token=XYZ
You can test this by changing an alarm and keeping watch on the device in HE to see that the command is triggered at the correct time before the alarm is due. The next steps would be to setup any RM rules, etc, if needed, to respond to the command being triggered, such as dimming lights, activating a scene, etc.
Hope this helps,