We often just used a big tube patch on the inside of a tubeless 4wheeler tyre using the normal adhesive. A sleeve is better as it's thicker than a normal patch and doesn't get pinched by the split. There is special adhesive for sleeves but just regular tube patch adhesive will do if you have the area roughed up and clean and primed.
If you've had goop in the tyre before, it's hard to get the sleeve/patch to stick.