PP Boot
PP Boot v1.5 seems to be unique to the Conexant Solos CX946xx board as used in the Linksys WAG54G2
Commands
Boot can be interupted and a console entered by pressing space on the serial console early in the boot sequence.
Googleing shows commands for PP Boot versions >8.5 and above. The only one that seems to work on v1.5 on the WAG54G2 is "netboot"
Preliminary investigation shows that the default config of PP Boot on WAG54G2 simply tries to boot the kernel at rom offset 0x20000