Separation Anxiety for Dogs....?

Just got an 18 month old boxer. She is doing great, very smart, learning very quickly, its really amazing. I've had her for 4 days, and she is better around other dogs, doesn't bark in the house, sits/lays down/stays when we ask her, and now even rings a little bell by the door with her nose when she needs to go outside. Overall, its been great. She doesn't even care to chew plants/furniture/shoes or anything like that....so far!

Now comes the hardest part: going back to work. She is crying like 2 minutes after I leave, and I can hear her starting to want to get crazy inside! Outside is not an option, right now. She'll be ok inside for 4-5 hours at a time if we can get over this hump! How can I do it?

PS. I am also trying some crate training, but that will take some time also I know, so any suggestions on how to speed up that process would be great! Thanks.