You can see this mountain from Kinlochrannoch and the day after i arrived, last October it was covered with light snow. Hike up it from the Forestry car park at the Brae of Foss and it is only around 3 miles to the top so allow 2 hours for the climb. On a clear day the magnificent view will be worth the climb.
The best thing to do is leave your car at the car park at Rannoch Station, hop on the train, get off at Corrour and start walking back. The train will reach Corrour in about 15 minutes, passing some boggy scenery on the way. From Corrour( only one house there) walk eastwards along the track until you reach the youth hostel at Loch Ossian, then take the east side of the loch on the upper track which will eventually leave the loch and pass between a rocky hill, Meall na Lice and a higher one, Carn Dearg. The trail runs along side Carn Dearg and an hour later you should pass the old ruin of Corrour Lodge where you will see the railway down below to your right. Continue along the trail until you reach the road, turn right and in 20 minutes you will be back at the starting point. There is a hotel that serves food by the station but when i did the walk last October they were no longer opening at lunchtime. From Rannoch to Corrour i got the 8.45 am train, but there are a few more, best check the times.
Most peolpe would arrive at Loch Rannoch by car , train or bus via PItlochry, but there is a station called Rannoch at the western end of the lake. The views of surrounding of Glen Coe and other mountains are tremendous especially if they are covered in snow. A few trains a day stop at this deserted part of the country, there is also a pub next to the station but no longer opens at lunchtime. Also there is a local bus that takes you along the side of the loch but only to Kinlochrannoch i think