Sorry if its scruffy but the method I would use is to add a numeric field z to the table that holds x and y. Index on z and make the index active. Move to the record from which you want to start then :-
SCATTER MEMVAR MEMO
REPLACE ALL z WITH (x-M.x)^2 + (y-M.y)^2
Voila! The table is in distance order according to Pythagoras. Or perhaps I've missed something.