Thanks! Here is what I came up with. Its a block select script used to select similar blocks.
(defun c:foo()
(setq blkname (vla-get-effectivename (vlax-ename->vla-object (car(entsel "\nPlease select a block!")))))
(setq ss (ssget))
(setq i 0)
(while (<= i (- (sslength ss)1))
(if(/= (vla-get-effectivename (vlax-ename->vla-object (ssname ss i))) blkname)
(ssdel (ssname ss i) ss)
(setq i (1+ i))
)
)
(sssetfirst nil ss)
)