Just wanted to clear up that there are no microSATA cables found anywhere in the iMac.
The cable that goes to the DVD drive, and the connector that comes off of the motherboard for the SSD, is a slimline SATA connector. Its a combination of the standard 7 pin SATA data cable, and a 6 pin slimline SATA power cable. (6+7 pin = 13 pin).
More information can be found about these cables in general here, and specifically with the iMac, iFixit confirms that the Sony Optiarc is standard slimline SATA here: http://www.ifixit.com/Teardown/iMac-Intel-27-Inch/1236/2
You are right.
This is what I bought: http://www.deltaco.se/?itemid=(SATA-SLM104). It was called slimline sata but too large.
Then I bought this after comparing to the DVD-cable: http://www.delock.com/produkte/grup..._SATA_13pin_7pin_SATA_+_SATA_Power_84418.html
It is also called slimline but clearly different. It looks just like the micro sata they had in the store, but fewer pins and thus smaller. That is why I was confused. Thanks for correcting.
And thankyou very much for the pictures and description of how to do it, I wouldn't have tried without it.