All the IRS really needs for a successful efile from a 1099-B is the totals in four categories (usually referenced as Boxes A, B, D, and E). These are short-term reported to the IRS (Box A), short-term not reported (Box B), long-term reported (Box D) and long-term not reported (Box E). Most broker statements show those subtotals and you can just enter the subtotals and check that it's a "group" entry.
They'll probably ask you to mail in a copy of your broker statement with form 8449 and form 8453, but the return will process and be accepted before they get that and match anything up.
In any event, hang on to a copy of the broker statement in case you get audited and need to show the auditor where you got those subtotals!
