I remember some old school 'bitmap font' editors that edited 8x16 pixel fonts, or 8x8 pixel fonts.. they used just the keyboard arrow keys to move the target 'pixel' around and hitting spacebar would togle it on/off. it was actually some 'bitwise' code on 8 bit computers, but it was simple and worked,.. I guess if you keep the sprites small, like max 16x24/32 it might be workable. if the sprites are too big, hitting the arrow keys for movement might get very tedious.
and that's what I think.
P.S. if you meant just moving the cursor around for fine tune adjustments, that's what the zoom modes in most paint programs is for.