There is No Way you can manually offline activate using oem:SLP key + Certificate if you do not have SLIC 2.1 in bios. Advanced Tokens Manager only backs up your activation if you machine was activated then you can use it to restore only needed if you used retail or NONE:SLP Key or MAK key, It does not activate your system on its own without activation being backed up. You need to use Daz loader.
Well it was possible in the past (at least for me before SP1), but it looks like today not anymore. And yes I used a working backup with ATM. However I gave a try to Daz Loader as suggested by you and it worked, although I had to run it on every Windows partition to activate them all. Thanks for the help!
Why bother manually activating? That thread was left in 2011 because it's way out of date and can't activate half as many systems as the latest loader can.
I had to use that method in the past 'cause no loader could deal properly with multiple Windows partitions. However I have to confirm that nowadays your loader is doing the job great, although I had to run it on every single Windows partition.
Obviously you have to you there is no way a key and certificate installed on windows installation on one partition will activate windows on another partition that doesn't have key or certificate installed.