How can I script administrator permissions on a SSAS server?

I am an administrator for a bunch of SSAS Instances. Sometimes I need to install or migrate SSAS instances to different machines or even different AD domains (we have a couple of different AD domains in a trusted relationship ). Same as with sql server, I need to be able to export and import logins and permissions between instances. Also, as part of maintenance plan I like to save logins and permissions as well as backup ssas databases . I would to script the administration logins via script either T-SQL or Powershell so that I can automate it. at the moment, because I was in a rush I did it in this way: 1. Connect to the original server as administrator and script all the permissions into a mdx file. 2. Copy this script and run it on the target server. How can I script administrator permissions on a SSAS server?