Click on the "Keyboard" tab in the top menu, then click on the "Customize" button to enter the customization mode. On the left side, click on the "Macros" button to open the macro settings.
Click on the "+" button to create a new macro. In the macro editor, click on the "Record" button. Press the desired key combination Alt-0128 on your physical keyboard. Then click on the "Stop" button to finish recording the macro.In the macro editor, you can review and edit the recorded macro. Make sure it accurately represents the Alt-0128 key combination.
 Select the key on your BlackWidow Elite keyboard where you want to assign the Alt-0128 macro. You can choose any key, including FN-1. Click on the key in the macro editor and choose the Alt-0128 macro from the list.

Ahhh so it becomes a macro… ok, awesome :)

To program the Razer BlackWidow Elite keyboard to execute the ASCII character Alt-0128 (€ symbol), you can use the Razer Synapse software, which is the official configuration software for Razer peripherals. Here's how you can do it: 

Download and install Razer Synapse if you haven't already. You can find it on the official Razer website. 

Connect your Razer BlackWidow Elite keyboard to your computer. 

Open Razer Synapse and log in with your Razer account. 

Once you're in the software, click on the "Keyboard" tab to access the keyboard settings. 

Look for the "Customize" button or the button that lets you assign macros. 

Click on the "+" icon to create a new macro. 

In the macro editor, you will see a text box where you can enter the key combination. In this case, you want to input Alt-0128, which corresponds to the € symbol. 

To simulate the Alt key, you can use the "Modifier" function within the macro editor. Click on the "Modifier" button and choose the "Alt" key from the list. 

Now, you need to enter the numeric code for the € symbol (0128). To do this, you can use the "Keystroke" function within the macro editor. Click on the "Keystroke" button and type "0128."  

Save the macro and assign it to a key of your choice on the BlackWidow Elite keyboard. 

You might want to test the macro to ensure it works as expected. Click "Apply" or "Save" to save the changes made to your keyboard configuration. 

Once you have completed these steps, pressing the assigned key on your BlackWidow Elite keyboard should now execute Alt-0128, which will produce the € symbol. 

Please note that the exact steps and options in Razer Synapse may vary depending on the version and updates of the software. However, this general process should give you a good idea of how to program the keyboard to execute ASCII characters using macros.