According to the rules here, if the sentence contains an indirect object it should have an indirect object pronoun. Therefore, your original sentence should have been:
Léenos los libros a nosotros.
I have read other articles stating that if the i.o. follows the verb, this seemingly redundant, i.o.p. is not used.
Ignoring that, to replace the nouns with pronouns:
Affirmative sentence:
Léenoslos. (being an affirmative, informal command the pronouns must be appended to the verb. The 3rd, person, singular, present tense, indicative mood verb ending is used.)
Negative sentence:
No nos los leas. (being a negative, informal command the pronouns must precede the verb and the 2nd person, singular, present tense, subjunctive mood verb ending is used).
