PLINK with redirect input to menu ...

I am trying to use PLINK for automatic voicemail backup (Linux/Mitel), and when trying to redirect answers to menu prompts I am getting mixed results. Maybe the redirects are too quick, any clues or examples?

This will log me in.....

Code:
c:\Batch>plink -ssh 10.12.99.64 -l root -pw ****

I'd like to input an "S" for the main menu, then "L" for the next prompt, etc...

Code:
MAIN MENU
(M) Mailbox maintenance
(R) Report generation
(S) System maintenance
(X) Exit
If you need help later, type ?.
COMMAND (M/R/S/X):


Thanks all.