Basically the [walletname].keys file has your encrypted spend+view keys pair.
The [walletname] file stores the info about the incoming/outgoing transacions.
I don't know if you meant to do this for 0.8.8.6 or the beta. Since I had the beta running and it would take a while to get 0.8.8.6 running I copied and pasted my .keys file into the folder of simplewallet of the 0.9 beta and it still didn't recognize it as an existing wallet when I started simplewallet. I'll have time tonight to do it for 0.8.8.6 if that's what you meant.
@Nik4692, It was seemingly straightforward so I have no idea what I could have done wrong