After you enter the city state and it asks for the street name enter IN- for the dash you will need to press the "SYM" button, then 49 will show up as a choice.
In this particular case select S IN-49, then put the house number in.
Unfortunately, there is no general answer I can give on how to specify a state route. Some states you put the state Initials (Like IN), some states you use "hwy", some states you put just the numbers. Then in this particular case there were 2 IN-49's the first one said the address was not valid, try the next one.
When I talked to the customer service folks a couple weeks ago they said that the next release (around May I think is what she said) the 700 will be able to also search using the zip code.