Domain computer security group's members into SMS Collection

I've got a long list of machines that have historically had an
application installed on them. All the machines are in a global
computer security group, in an Active Directory domain, and I have a
listing of them in a text file.

We now need to roll out an upgrade to the application, and we're
looking to use SMS to do this.
How can we build a collection from the computer security group?

We don't have a copy of "MakeColl.exe", from the Backoffice Resource
kit, and we've tried exporting, editing and reimporting the MOF file to
include the computer names to add (375 of them). Perhaps it's
something to do with the quantity, but the mmc application locks up!

I've seen solutions where people have recommended building a query, on
System resource, and System group name, but having run a query
displaying the system group name for these machines, the field is empty.

.