Do the accessories have to be disconnected to engage the starter?

Can’t really understand why you do not want to replace the ignition switch as is is not a complicated process at all plus it’s not very expensive. Don’t forget about the antitheft system - you’ll need to address that as well if you attempt any sort of bypass. As far as your question the answer is NO - nothing has to be disconnected. Good luck with!

The key cylinder is expensive but the switch body is not. What part do you need? Bypassing and doing all kinds of crazy things to circumvent how it all works is kind of on the side of crazy. Do it right. You introduce all kinds of safety concerns by bypassing and all that.