If I can build scsi as modules and have genkernel load it, I should be able to do the same with ide. This patch does just that based on a previous patch that I made in bug 46278
Created attachment 28397 [details, diff] ide is loaded from modules
IDE as modules is not recommended by the kernel developers, nor is it guaranteed to work at all. In short, you are on your own if you want to try to do this.