Getting custom shaders working with Iris

[awakaxis]

Apologies if this isn't the right place to ask, but I'm wondering if anyone could provide me some insight on what I'd need to do in order to get my mod's custom core shader working while Iris is running a shaderpack? My mod has an effect that I'm pretty sure cant be reasonably achieved using using a vanilla rendertype, and I'd really like for it to be able to render while using Iris shaders. I know Immersive Portals uses a custom shader while Iris is running (maybe im wrong??) so I've been giving their code a read, but I figured while I do that I might as well ask here too. Thanks in advance for any help!