accessible music app
Unfortunately, I don't know of an easy way to replace iTunes, even when jailbroken. However, If you install both iFile and Gremlin Framework from Cydia, it's possible to import music from your computer to your iPhone without using iTunes. Once both are installed, simply upload your music files to a directory on your phone and use iFile to import them. Your music will then be available in the standard music app.
To import using iFile, open iFile and locate the files you uploaded. When VoiceOver speaks the name of one of the files, slide your finger to the right until you find the more info button. Double tap that button, and scroll down until you find the button labeled add to iPod library. Double tap once more, and the song will be added to the music library. Repeat until all songs have been added.