A key step in the import process is to bring the bilingual content in an Excel file into a memoQ project as a "translation document" and then send that content to LiveDocs from the translation files list. Direct import to a LiveDocs corpus of bilingual content using the multilingual delimited text import filter is still not possible despite years of asking the development team for memoQ to implement this.
This is irritating, though in the case of a EUR-Lex alignment which may be slightly out of sync and need fixing, it is perhaps all for the best. And in some other situations, where the content may be incomplete and require filtering (in a View) before sending it to the corpus, it also makes sense to bring the file in as a translation document first to use the many tools available for selecting and modifying content. However, in many situations, it's simply a nuisance that the files cannot be sent directly to a LiveDocs corpus.
In any case, I've now done a short (silent) video to make the steps involved in this import process a little clearer: