Info, please, on power cord burn-in

I don't think you actually mean "short" the power cord as that term implies connecting positive to ground.

If your asking how to connect several power cords together on one piece of equipment to facilitate break in, you would need some sort of adaptors to connect these together.

Are the cords your asking about the typical USA 120 Volt grounded male on one end and IEC on the other?

DON'T DO IT! DON'T DO IT! That is a direct SHORT and will blow a fuse. If you want to burn-in your power cable with out your equipment buy a Burn-In Adapter ($19.95) FROM www.musicdirect.com. You can burn a light blub, fan, ect. for several weeks. Bob Crump said it would take 4 week to burn in his power cables. I don't know why, but it does improve the sound.

Better yet, save yourself about $15 (definitely available below the list price) and buy this, commonly available at most electronic supply stores, which is exactly the same thing but not marketed to audiophiles who are willing to pay ridiculous prices:

http://www.startech.com/ststore/ItemDetail.cfm?ProductId=pac100&mt=

I'd recommend the refrigerator as it has done more to burn in cords (even ones that have been on equipment for a few years) effectively than anything else I've used. I'd be prepared to leave it on your refrigerator (even if it's a newer model, energy star compliant, blah, blah, blah) for a couple of weeks.