The creature would need a voice that is compatible with marriage, There is a mod on the Nexus, called Marry Me. The cheat room mod has a spell with dozens of options that affect NPCs you cast it on.
NOTE: Please read through the FAQ and Troubleshooting link below before posting issues with the mod You can now marry any of the Caravan Khajiit or J'zargo without any console commands. Companions and Followers focuses on adding multiple followers instead of one really detailed follower like some of the other mods on this list. However, for fans that have been playing Skyrim since its release, they might have exhausted all the options they're interested in.
