Where to find Kernel Source for Sharp ROM 3.10 (SL-5500G)?

[dhns]

Hi all,
I am searching for the original 3.10 kernel sources (2.4.18-rmk7-pxa3-embedix). Unfortunately, the ZUG HowTos point to a Sharp Japan site which has only sources for the A, B and C series.
And the ZUG Downloads has a section called kernel_source but despite its name it contains installable binaries and no sources...

-- dhns