Frankly, these systems are not designed for over 500 transactions. If you have many hundreds of transactions, your best option is likely to be to append a schedule and summarize the entries on the actual tax forms. If you have only one brokerage account, not something to take for granted if you're doing an average of two or more trades per market day, then you may find it easiest to use the 1099 itself as an appended schedule. Think about it. If TT is going to logically support that volume of transactions, they're likely going to be creating an appended schedule anyway.
IRS pub i8949 says in part, on page 3, ...
"Instead of reporting
each of your transactions on a separate
row of Part I or Part II, you can report them
on an attached statement containing all
the same information as Parts I and II and
in a similar format (i.e., description of
property, dates of acquisition and
disposition, proceeds, basis, adjustment
and code(s), and gain or (loss)). Use as
many attached statements as you need.
Enter the combined totals from all your
attached statements on Parts I and II with
the appropriate box checked. "
