If you mean switching from the staff roll to the enemy credits directly, this does it:
if read1($00FFD5) == $23
!addr = $6000
!addr = $0000
I made so the song is changed immediately to the last credits theme: the transition is a bit weird (since it skips the "Yoshis are home" theme) but it works. If you just want one song for all the credits then you can remove the two lines before the RTS.