You don't need to do it unless the scent glands are impacted.
I have had Pippin's scent glands cleaned once, and Benji's never. I check them, of course, just in case, but lots of bunnies never need it done.
If the scent glands don't look swollen or impacted then I wouldn't put Butsy through the stress if he's not a very cuddly or relaxed bun when it comes to handling.
If you really need to then I would definately get a friend to hold him and you to do the cleaning- they are so sensitive down there I would want to be as careful as possible and have him struggling as little as possible.
Warm some cotton wool balls or something equally soft (Q tips I have heard of but I don't know what these are?) and gently wet the black 'beans' in each scent gland and take your time gently warming them and very carefully separating them from the skin, because they will likely be dried stuck to the skin, which is very sensitive. Keep easing it off with warm water and gently sort of, put slight pressure around the side and ease it out.
With trancing I don't fully trust it. Because they can 'snap' out of it and leap out of it which can be quite dangerous if you are clipping nails etc. so I have formed a way that is perfect for me and my buns.
I sit with my legs straight and apart, and sit bunny between my legs as close to me as possible, facing in the same direction as me. Then I lean forward so my chest is against their back and put one of my hands around their front paws and try and get as good a grip as possible around their back to. Then I pick up their front and just pivot them to leaning back on me so their belly is exposed (up against me), they are sitting on their bum, and i have firm hold of their whole top half. Then their legs and claws are completely accessible and they just can't jerk away. If they try and jerk they just don't move far. So I can quickly snip their claws. It's SO quick and SO easy and I know they can't suddenly leap away and risk getting cut or catching my skin with their claws etc. And this way it literally takes one second per clip- so about 20 seconds.
Hope this helps
Jen