Walker and Pickard will join the team at the weekend before they head to London where the riders will spend three days training on the revamped Olympic track.
From there the group head to Birmingham for the world championships starting on May 24.
"It is a busy time for us but really important," said BikeNZ BMX national coach Ken Cools. "This weekend is a good opportunity for the squad to compete on a challenging course.
"Marc [Willers] has had some ill-fortune this year so far but this is a track he absolutely nailed last year. So he is looking to step it up this weekend."
Cools said the opportunity to practice on the London track is vital.
"There are apparently some significant changes to it from when we rode in the test event last year. It will be a key few days for us to begin to dial in looking ahead to the Olympics."
Willers will lead a BikeNZ team this weekend that includes Kurt James (Cambridge), Nic Fox (Gisborne), Daniel Franks (Christchurch) and Matt Cameron (New Plymouth).