Add Endnote* formatted records to mx by pasting them into the text box. First click "verify" to review the result, then click "save". If you modify the text after verification but before save you'll have to verify it again.
NB. Endnote-formatted = "Endnote Export" (*.enw, *.ens) or "Refer" style for recent versions of EndNote.
To do this from EndNote, export a text (txt) file in endnote-export format:
export> select another style> Refer style.
Note that not all fields in the most recent versions exist in the Refer format, so there is the risk of data loss. Note also that keywords are potentially lost as well unless you set them up for "notes" (not good since ref is shared among projects) or "tags".