If you have an X client (ie GUI) for your Linux system then there should be a utility tool in the control panel of your client to do the trick. The main file that get's maniplated is the "lilo.conf" file in /etc (i think!!). Since i'm not near a linux system right now, i can't give you an exact answer, but i'm sure that in lilo.conf u can change the waiting time before the system automatically goes into linux. Remember this time is calulated as tenths of a second (therefore 600 is a minute).
best o luck