As far as I know, you cannot use blocks in Grasshopper.
Pretty much similar to the script linked above, I generally use for this purpose this Python snippet:
import rhinoscriptsyntax as rs
pts = rs.GetObjects("Select points ...", filter=1)
blockName = rs.GetString("Name of block to copy ...")
for pt in pts:
rs.InsertBlock(blockName, pt, [1,1,1], 0)
print "No valid block name entered."
print "No points selected."
(“Tools > Python script > Edit” to run a script)