they are only toxic if you eat the plant parts directly. so you can grow things in the soil next to them and the composted yew material can be used in the garden without any ill efects. The berries are regularly eaten by birds and they do not suffer..

I would be wary of using Yew clippings in compost. They will not harm plants but if animals have access to the dying clippings they are very toxic. The birds are not poisoned by the berries because they they do not digest the seed itself. I have read in an Irish newspaper of a girl who comitted suicide by drinking yew 'tea' (at Christmas)

I must say though that as part of the nutrient cycles yew leaves are eaten by decomposers as part of the normal diet of these organisims. There are not specifically yew decomposers as such. If they were not decomposed then the natural leaf droppage of the yew would be piles metres high.
So they can be composted with out fear.

A well known company have been collecting Yew hedge clippings in the UK since 1992, for use in a cancer treatment which is particularly active against ovarian and breast cancer. So it has good uses too!