The cutoff keeps defaulting to 0.05 in Jmol
The syntax is 

isoSurface id saSurface radius


So you should use 

isoSurface id saSurface 0.008


You can use the optional id for giving it a name.

You may also want to see their reference page 

Edit 1: Have you tried using DX files ?
I am not an expert in using DX to render the required results but here is the reference  : 


  DX, as Cube, defines a three-dimensional grid of points in space. At
  each point is a number (a "scalar value"). This set of point values is
  then used by Jmol to define an "isosurface" -- the surface separating
  points having values greater than a given cutoff from those that have
  a value less than a certain cutoff. A typical application is molecular
  orbitals. The phase parameter of the isosurface command allows bicolor
  rendering: one color for "points greater than x" and another color for
  "points less than -x". Jmol can read DX files and re-export them to
  much smaller JVXL files.


Quoted from here