Jeez, what a bunch of divas in here.

We're ready to put on a show over here.
Anyway, Hollywood makes musicals that are previously established on Broadway. Yes, even today. Just like Broadway apes all the Hollywood hits in greater numbers (
Toxic Avenger: The Musical, anyone?) but I digress. So the question is, can an unknown writer sell a spec script that is a musical?
No. Any more than one can sell a western* or historical epic, the financial expense is too great to risk on unproven talent. Would you let a kid in the mailroom sit on the board, even if you thought he was exceptionally bright and charismatic? Of course not, because he hasn't proven himself in business in a meaningful way. Do you think Hollywood is different?
Some indie guys make musicals on their own (
Beach Blanket Psycho, er
Psycho Beach Party anyone?). But it remains a Broadway thing. (Yet another reason to love Gotham.)
I would suggest coming to London or NYC or another city with a strong theater network and staging it as a play. Or filming it low budget and marketing it the indie way. At least it will get done. I would suggest these things to the OP too, if only he were interested in participating in a discussion, but apparently not.
*I know, I know,
Brigands Of Rattlebourge. I am amazed that he did that. Being a fantastic writer still counts for something in Hollywood, I guess.