Actually there's a really easy solution for this. Make an INJ file for the morph(s) as usual. Then make a second file like so:

{
readScript :Runtime:Libraries:Character:OriginalFigureCR2.cr2
readScript :Runtime:Libraries:Pose:YourInjections:YourINJ.pp2
}

Obviously replacing the paths with the right names. The new channel should be inserted with the others, at the bottom of the dials. Optionally you can inject an INJ pose over an existing morph by using an existing targetGeom name, but you'll be removing the existing one. XFX-3d -- Join Now

I'm the asshole. You wanna be a shit? You gotta go through ME.