James, I thought you might be interested in this brief account of the training given to the sharpshooter battalion in Mahone's Brigade (Army of Northern Virginia) --

The battalion was armed with long-range, small-bore Enfield rifles, and used a long English-made cartridge. We never used any ammunition made by the Confederate Government. There were, besides, two glove-sighted rifles for use on special occasions, which were valuable additions to our armament. I have frequently fired these with entirely satisfactory results.

During our occupancy of winter quarters, previous to the Mine Run engagement in May, 1864, our time was spent in perfecting ourselves in the skirmish drill by signals, and in rifle-target practice at different ranges—from fifty yards to 1,000 yards—and so proficient did the men become in estimating distances that, although the chain was used to confirm their calculations, its use was finally discontinued as being unnecessary. Every day these practices were kept up under strict discipline, and systematic regulation and improvement in marksmanship noted, and such men as failed to make satisfactory progress were returned to their companies and others substituted, so also, when the casualties of battle decimated the ranks, other details were made from the regiment strength. Thus, when the campaign of 1864 opened, this body of 180 officers and men, selected for special duty and because of eminent qualifications for such service, appeared thoroughly trained and fully equipped, and their subsequent record proved that they were absolutely invincible in every engagement in their history, never having been driven from their lines in any single engagement.
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Capt. John E. Laughton, Jr., "The Sharpshooters of Mahone's Brigade," Southern Historical Society Papers, XXII:99-100 [1894].

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It's clear that marksmanship ability and training was considered to be essential, and, thus, that long-range sharpshooting was, indeed, an important element in the sharpshooter battalion's bag of tricks.

Philip Katcher's "The Army of Robert E. Lee" states that two of the training manuals used by some (at least) of the Confederate sharpshooter battalions were Wilcox's Rifles and Rifle Practice and Mahan's An Elementary Treatise on Advance-Guard, Out-Post and Detachment Service. The latter was described as "an ideal manual for practical use by sharpshooters, dealing with such subjects as estimating distances and serving in small detachments before an enemy force. Indeed, training in just such subjects as Mahan covered was given extensively in the sharpshooter battalion in McGowan's Brigade, as well as a great deal of target practice, practice in fighting cavalry, and bayonet drill."