We use this great script http://deptive.co.nz/remote-assistance-powershell-gui-for-xenapp/ for remote assistance on a Citrix Farm , however it does not work with 7 out of the box , to get this  working with XenApp 7 follow : 

Install SDK’s from the MSI’s on the CD (Bust the XenApp 7.x ISO)

1.    To import all the cmdlets, type:

http://support.citrix.com/proddocs/topic/xenapp-xendesktop-75/cds-sdk-wrapper-rho.html?_ga=1.166625726.1062411362.1436824830

Modify Script to point to the Data Collector:

http://support.citrix.com/static/kc/CTX127254/help/Get-BrokerSession.html

Add User to the Citrix Administrators in Citrix Studio

Add User to the SG_Remote_Assist_Allow Group (this is a member of the Offer Remote Assist local group on Server)

http://discussions.citrix.com/topic/361303-where-can-i-download-the-xd-sdk-for-75/