Auchinleck House was uninhabited and not taken care of for a few decades until in 1986 it was turned over to the Scottish Historic Buildings Trust (SHBT) by a descendant of the 18th century Boswells. The SHBT did some renovations on the building, before in 1999 Auchinleck House was sold to the Landmark Trust.
It has since been thoroughly renovated and is now open both for visiting and for staying, accomodating up to thirteen guests at a time.
Auchinleck House is located some 4 km west of the village of Auchinleck, and it is most easily accessible by car. If you're not driving yourself, you can take bus X76 from Glasgow via Kilmarnock and get off either at Auchinleck Main Street or a bit further on in the town of Cumnock. A cab (one-way) will cost you around £15-20 from Cumnock. Don't forget to bring your wellies, as the grounds can be rather muddy.
If you decide to stop by Auchinleck itself, don't forget to visit the village church, next to which is the Boswell Mausoleum, the biographer's final resting place. The pub across the road from the church is named Boswell Arms, but apart from that it has no connection with Boswell.