I flinted a UST Maxxis the other day and managed to fix the small cut.
I got some flexible Loctite superglue, the stuff that dries without hardening that they recommend for rubber. Clean the tyre with washing-up liquid inside and out till it squeaks and dry well. Put a tiny bit of glue on the inside to seal the cut / hole as best you can, keeping the tyre flat / in a natural position as it dries – let it dry under pressure ideally. Then glue a small (<1p pc size) bit of inner tube over that area. Let it dry again. Then open up / flex open the outside of the cut and seal it shut with a dab of glue, less the better.
Did this the other day, re-seated and latexed the tyre next morning and inflated, it’s been fine for 30-odd miles at 20psi and looks like a solid repair.
HTH