I have actually followed the one ArcaneMagus points to with good results.
Since my diff at the moment basically is a full backup just follow the wiki and you should get your server up and running again.
But beware i'm about to change the diff backup in near future and that puts more demand on how backups are done, but this i will tell and show on my blog when i have updated the script.
Good luck and don't give up if you cannot get the restore to work the first time, sometime it doesn't work directly, but have faith.
/Marcus | 
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