you can't have binary numbers.. but you can have integer variables and there are bitwise operators for them..  
do you thing this would work for you?
integer counter
analog begin
  @(cross(V(clk,clkb),+1,ttol,vtol) begin
      counter = (counter +1)%(1<<7);
   end
end
---
of course if you'd use Verilog-AMS you could
use your normal Verilog construct for the counter..