Yeah, you'll need to call and ask for the AS confirmation code. The SQ confirmation code isn't going to do much for you here. They can look you up with the SQ ticket number...

Don't know why you'd be freaked out about calling AS- I have to do this all the time with BA and AA tickets (which also get an AS confirmation code that isn't the same as the one on the airline you ticketed with). It gets handled fine.