You could record each day onto the card using the manual input facility - but that’s way too much faff (and far too likely to result in erroneous input(s) being recorded).
In order to remain totally within the letter of the Regs, you should make (written) manual entries for each day on a piece of printout paper (or on the back of a paper chart), keeping one copy of each with you for the next 28 days and handing another copy in to your employer (alternatively keep just the one copy with you and then hand that copy in after 28 days).