OK, I just found out how to register the DLL as part of Today. I'm gonna take my iLauncher as an example. So put all the DLL from the .cab install file and extract it to OEM like usual. Flash ROM and go to HKLM\Software\Microsoft\Today\Item and create a new key called "iLauncher" with the following sub keys:
type | Name | Value
----------------------------------------------
string DLL iLauncher.dll
DWORD Enabled 0 don't enable yet, enable yourself
DWORD Flags 0
DWORD Order 0
DWORD Options 0
DWORD Type 4 don't know what this means copied from other.
Close regedit, and go to settings - Today and you should see iLauncher and tick to check it and hit OK. iLauncher will now load.
So far my custom ROM contains
netcf2 from imkokeman
magic button imkokeman
wm5menu kokeman
iLauncher
Wisbar Advance with Crossbow theme
PHM Editor
SKTools
RegsvrCE
TotalCmder kokeman
More to be added...maybe pocketbreeze and such.