There is a great N-Back program on source forge for working memory training called Brain Workshop
I will use that for the working memory protocol & have been using it anyway
I also will be training with Vedic Math software for mental calculation - this also utilizes working memory but I will use the Math protocols with this software.
As for the protocols them selves there is a great deal of scattered information.
This PDF lists several relevant electrode sites
Great care must be taken in selecting the placement areas and the polarity of the electrodes.