"How can I get interest income on line 1 of 1041, if I don't have 1099s?"
The figure you enter on Line 1 of the Form 1099-INT Worksheet will wind up on Line 1 of your 1041 (see screenshot).
It is actually irrelevant how the interest is entered since the 1099 in the program is strictly for your records only; it does not get transmitted with your return.
