There is a way around it, but the reason those discs are model locked is because they may not necessarily contain the proper hardware support for other models. For example, a Mid-09 MBP would come with a 10.6 disc, but a Mid-2010 iMac needs at least 10.6.3 to boot without kernel panicking. If the iMac came with Lion, which would explain why you don't have a copy of any restore media, then odds are Snow Leopard will not work because of changes made to the hardware configuration that are only reflected in Lion.
This is largely the same song and dance people have had to come to understand when they buy a new PC and want to install XP on it. The drivers quite often simply are not there to support the hardware.
Further, if the iMac shipped with Lion, then you do not have a license to use Snow Leopard on it. Apple doesn't have anything like Microsoft's activation system, but you're still only allowed a single copy installed on a single computer. You can't just go buy a retail 10.6 disc and install that on as many computers as you want... And remain on the right side of the license agreement. There's nothing stopping you technically.
So even if I told you how to get around this issue, it probably wouldn't do you any good.
Hi all.
I'm new here. I need help.
I have a Snow Leopard Install Disk for the 13-inch Macbook Pro model.
I also have a 21-inch iMac. I have OS X Lion installed on both. I have Snow Leopard installed as a partition on my Macbook Pro, which I installed via the install disk. I want to do the same thing for my iMac but I am unable due to (seemingly) my install disk is for a Macbook Pro and not for an iMac.
Does anyone know a way around this? Why won't this work? I was thinking I could change something in the package contents to alter it to allow it to work with an iMac?
I'm lost. Please help.

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