External keyboard and make a full backup or at least get off important files. I assume you have a desktop at work or a mate who can lend you a keyboard. I hope you can put the machine back together and get it booted, you shouod have made the backup before you took it apart 😉
Personally I would not do the wash it out thing. Take it to a repair shop and get a quote for a new keyboard – it’s probably not worth repairing though. New machine or use it with an external keyboard – you can probably get a wireless one.
I killed my Apple wireless keyboard trying to clean it with Cillit Bang ( doh ! ) despite tinkering with it it never worked properly again.