Is it possible to force partioions to be primary or extended in Anaconda | unverified

Issue

At the moment anaconda is choosing which os slice to place either in primary parition or on extended partition.

Which is a problem because its put / on extended partition along out /local/0. We want the option to extend local/0 so we want to be able to force disk layout so that -

partion 1 is /boot
partiion 2 is /
parition 3 is /var
extended is 4
partition 5 is swap
parition 6 is /local/0

Can we do this ??