First the muscle memory must already be familiar with the chord progressions, if you're compin' along to the melodies, the chords could be anchored to the lyrics and melody of the song.
Use the mnemonic device called the method of loci. The advantage of this method is that you can jump between from verse and chorus by just stepping into the room you've associated the verse or chorus with (in your mind).
Use real objects in the room, that are usually there, (e.g. tv, couch, rug in the living room, and toilet seat, shower in the bathroom) to anchor an initial strand of a story. The story is just a sequential translation of the lyrics into memorable narrative. The more outrageous, the more memorable.
If you speak multiple languages use translations of words and the phonetic information to link words together.
Manipulate the object translation of words in the lyrics in the space e.g. explosions, actions etc. Use a phonetic approximation of the word if it isn't an easily translatable object. It's important to anchor to existing objects in the space, e.g. tv, couch, toilet, showerhead, cupboard, dining table etc. One could also use synonyms but this would tend to require some thought (introduce a new layer of translation), which would take extra time.
If you speak multiple languages use translations of words and the phonetic information to link words together.
It's key to reduce the recall-time, to stay in the rhythm of the song, even before you actually need the information.
I discovered a trick to optimize on recall time, by grouping triggers together for the next word which fall on the start of the musical phrase, before you actually need the trigger. For example, you need to recall B in the following melodic phrase, you need A in the current melodic phrase, so you chunk mnemonic triggers for AB together, before you actually need B. You could also memorize a meta-trigger for B, instead of the real trigger for B.
It's important to walk through (in the mind) the rooms, during practice, as if you're walking through different parts of the song, so the sequence of the verse, bridge, chorus is easy to traverse. I use my friends homes to memorize songs.
For instance a pop song of 2 minutes, there would be at most 3 distinct lyrical parts e.g. verse, chorus, bridge. If certain parts occur together like two verses followed by a chorus, this could be chunked together in one room, then the rest could be chunked together in the following room; a song could theoretically require two rooms. Two songs could theoretically could fit into a locus of 5 rooms, mnemonically speaking.
You can also try to engage your limbic brain in memorizing the lyrics, by imagining the sensations produced by the lyrics. You can imagine feeling a warmth on your cheeks, when you sing the word "Hot" etc.
It's also good to use multiple non-conflicting triggers (e.g. sensations, images, narrative, onomotopeia, synonyms), in your story to encode the lyrics, eventually the strongest trigger will remain.
It's fairly obvious that one should also practice recalling the triggers.
