At this moment the Nanopore technology is not ready yet for RNA. So you need to prepare double stranded cDNA, in order to ligate the sequence adaptors.
People at the ENS are currently testing RNA-Seq on the MinION (not from single cell though). Their contact info can be found here: www.genomique.biologie.ens.fr
You should try to contact them early 2017 to see if they have some info to give you.