SSL CA Install
From WPKG | Open Source Software Deployment and Distribution
There are probably lots of ways to do this.
You will need CertMgr.exe. It's part of .NET Framework 2.0 Software Development Kit - you don't need the entire kit on your clients or in your WPKG installation, only CertMgr.exe.
CertMgr.exe is documented here. Basic usage as follows:
%programfiles%\Microsoft.NET\SDK\v2.0\Bin\CertMgr.Exe /add ca-cert.der /all /s /r localMachine root
This would install all CAs in ca-cet.der globally, for all users.
Example:
<package
id="ssl_cert"
name="ssl certificate"
revision="1"
reboot="false"
priority="50"
execute="once">
<install cmd="%SOFTWARE%\pkg\ssl\CertMgr.Exe /add ca-cert.der /all /s /r localMachine root">
</install>
</package>