You can enter that information as if you received a K-1 instead of the GIS that you actually received.
Box 1 on the K-1 (1041) is for interest income which will flow to Schedule B, as will Box 2a for dividends.
Boxes 3 and 4a on the K-1 (1041) are for short-term and long-term capital gain, respectively, which will ultimately wind up on Schedule D.
