the glide flag is used to make enities glide allong walls etc, to do what you want and make an entity walk over a table you would need to use c_trace. C_trace to a position below the player and then move tha player on the z axis. like this:
Code:
vec_set(temp.x,my.x);
temp.z -=600;
my.z -= c_trace(my.x,temp.x,IGNORE_ME|USE_BOX|IGNORE_PASSABLE)-3;