Hi there,
You could try looking on the interactive map at the Ordnance Survey of Ireland site,
www.osi.ieyou can pan around, zoom in etc. I haven't looked at the Kilmallock area in great detail, but I did spot Ballymacshaneboy, so could be worth a look in any case , just to familiarise yourself with the area.
Another idea might be to contact someone at Kilmallockonline, and find out if the local post office might know of the name you're searching for.
I imagine Ballyshaneboy might be the name of a farm or small hamlet, a place name rather than a townland.
Good luck!
Mags
P.S,Also have a look at the place names of Ireland site, it's great:
http://www.logainm.ie/?text=ballymacshaneboy&placeID=30807