This Powershell script generates a Windows Form that allows you to import a list of computer based on a text file to a specific collection in SCCM 2012:
When launching the script, it generates the list of collection of your SCCM infrastructure. You can select the text file by clicking the search button to get the content of the file.
Then you can click the import button to create the rules to add the computers to the selected collection.
Before launching the script, you will have to modify the following variables :