First, you need to create a XML file, for example, dr_eye.xml

<?xml version="1.0" encoding="UTF-8"?>
<openServiceDescription xmlns="http://www.microsoft.com/schemas/openservicedescription/1.0">
 <homepageUrl>http://www.dreye.com/</homepageUrl>
 <display>
  <name>Dr.eye Dictionary</name>
  <icon>http://dict.dreye.com/ews/favicon.ico</icon>
  <description>Dr.eye Dictionary</description>
 </display>
 <activity category="Translate">
  <activityAction context="selection">
    <execute method="get" action="http://dict.dreye.com/ews/dict.php" >
     <parameter name="w" value="{selection}" type="text" />
     <parameter name="hidden_codepage" value="01" /> 
     <parameter name="ua" value="dc_cont" /> 
    </execute>
  </activityAction>
 </activity>
</openServiceDescription> 

Then, add an Install Accelerator button that calls AddService when clicked. (Installing an Accelerator XML file from the local system is not allowed.)

<button onclick="window.external.addService('http://127.0.0.1/dr_eye.xml')"> Install Dr.eye Accelerator</button>

Install Dr.eye Accelerator

Reference: OpenService Accelerators Developer Guide