Extend VADER Sentiment Lexicon with individual words

Hello,

im using the VADER algorithm to perferform sentiment analysis. However, i have some domain specific words that i want to add to the lexicon with their respective sentiment score. I found the function:

compoundScores = vaderSentimentScores(token, 'SentimentLexicon', lexica)

but it overrides the entire Lexicon instead of adding the words. Is there a way to extend the lexicon?

Regards,

Simon