Give this a try to install your update via Managed Software Delivery:
1- create a folder somplace where your Altiris identity account has access, store the file to be installed in that folder
2- create a batch file with the command line to successfully install the update
3- import the contents of this folder into your software depository selecting the batch file as the install file
https://www-secure.symantec.com/connect/articles/symantec-software-management-71-best-practices-part-2
4- follow steps in this article to create the policy
http://www.symantec.com/business/support/index?page=content&id=HOWTO62551
note- in some cases I have found it works best to specify a specific directory location in the policy to store the downloaded file, then modify the batch file to install the update from that specific location