[Villodre]

I remember that, in order to play S3&K in emulation, you just had to concatenate both games in a COPY S3.BIN + S&K.BIN way (if you used DOS) so I mostly knew the answer already.

But man, that answer in the Stack site was excellent. Informative, long but concise, and very fun to read.

[LeoPanthera]

Many modern Genesis emulators have the ability to select a second ROM to "connect" to S&K, allowing you to connect arbitrary carts, if you want to.