How do you charge an electroscope positively using both a positively charged rod and a negatively charged rod?

Here's how to charge an electroscope positively:

a) Using a positively charged rod:
Bring the positively charged rod into contact with the electroscope's cap. Electrons from the electroscope will transfer to the rod. The electroscope loses electrons and becomes positively charged. Remove the rod.

b) Using a negatively charged rod:
Bring the negatively charged rod close to the electroscope's cap without touching it. Electrons in the electroscope are repelled to the leaves. While the rod is still in place, touch the electroscope's cap with your finger to ground it, allowing electrons to flow from the electroscope to the ground. Remove your finger, then remove the rod. The electroscope is left with a net positive charge.