I could not find out what arguments are supported by busybox's built-in "read" command in the ash applet. At least -p and -s seems to work. Bash prints a short summary with "help read". The command help does not have an "ash" section.
This is more like a not very critical feature request. I prefer bugzilla to be used for tracking bugs and important feature requests. Sorry, I'll close this one as WONTFIX. If you have a patch which implements this, feel free to reopen and attach it. Or send it to the mailing list.