To update, you can you old manual : manual
or shorter way:
1) make sure you have dsmos/appledecrypt and appleintelcpupm disabler kexts installed to /Extra
ich10r users - you dont need legacy kexts for ich10/ahci anymore, 10.5.7 supports ich10r out of box (since new macpros has ich10r), need only legacy ahciblockstorage, to fix orange icons.
Important notice, legacyhda may not work with newer applehda.kext from 10.5.7, you will need either make sure you legacyhda works with 10.5.7 or use applehda.kext from 10.5.6 (alc889a legacyhda from stickpin and friends need to be updated)
You still need to carry abotu whatever custom drivers you have.
If you use chameleon, or other bootloader with smbios replacement support, better to make identify of your machine to be some imac or something else, MacPro4,1 identify may result in kernel panic, or you need to remove AppleTyMCEDriver.kext with this script, durring installation :
Good luckwhile sleep 1 ; do rm -rf /System/Library/Extensions/AppleTyMCEDriver.kext ; done
How to update to 10.5.8
install this Dsmos.kext ( a bit updated to be present in mkext)
create backup of Extensions folder. just in case:
update !sudo cp -rf /System/Library/Extensions /System/Library/Extensions_old
if something is wrong with your drivers after update - u have a backup
for radeon HD 48×0 users, binary of Motmot wasnt updated, so if u used patched framebuffers, should work fine still.
for radeon HD 4870×2 4890 4830 users - you will loose qe/ci/3d after update, wait for proper patch.
Dont remove AppleIntelCPUPM.kext until install finished, or it will stop with error.
If your using a patched kernel remember to reinstall it again before reboot
Update: Here some fix