The only information I could find is a suggestion to use Stannous Chloride for reduction sensitization. IIRC, it is rather rapid acting and prone to fog.

Stannous Chloride is such a strong fogging agent that it is used as the current reversing or fogging agent in the E6 process, so exercise due caution using it in the darkroom.

I have no information on suggested amount to use, but since it is a surface effect just like Sulfur or Sulfur + gold sensitization, the quantity is dependant on surface area.