I find it easier to take the SCV off the tractor and work  on it on the bench. If your outlet is leaking around the hose, you might get away with only an o-ring and a backup ring or a quad ring depending on model. No need to remove the SCV from the tractor if that's the case.

If the SCV is leaking elsewhere, I would buy a repair/ seal kit. It comes with all the orings and seals you need to do the job, including instructions. You might need to order the packing which goes between the SCV and the manifold.  Not very hard to do. Good Luck.