In reply to Kent's 550-9 declared, Warwicks crashed to 107 all out with McLaren taking 5-24.
The second innings saw 125 not out from Darren Maddy but Warwickshire will still in trouble on 187-5 at the close.
In the test at Lords, England were 282 all out with Ian Bell making nine. Kevin Pietersen was in good form (134) and gave England a lead of 379 to take into the final day and a bit.