They way we do it is we open the DCS dialog box, click the "Print to information window" icon, and do "file" - "save as" - "filename.txt". As far as editing goes, most of the information in the DCS log comes from the part attributes. You can try editing those.
Is there a way to edit the text file and re-import the file so that components in the assembly gets these attributes? e.g. Name of the engineer is changed in the text file, re-imported into NX and affects the title-block?