you can try passing multiple Ids with the Query q=id:(document_id1 OR document_id2 OR document_id3)
:-
e.g.
http://localhost:8080/solr/select/?qt=mlt&q=id:(document_id1 OR document_id2 OR document_id3)&mlt.fl=[field1],[field2],[field3]&fl=id&rows=10