Actually found it. Somehow me ànd several colleagues of mine overlooked it: CreateCacheRefreshPlan Method is the solution...
It does not look nice (but hey, I am not a developer) and half of it are shameless rip-offs but it DOES do the trick.... :)
Thnx and kudo's to all the people who posted the tidbits I needed...
$reportServerURI = "http://localhost/Reportserver"
$ReportPathWildCard = "/";
$NameSharedSchedule="NAME OF SCHEDULE";
# init WS proxy
$reportServerURI2010 = "$reportServerURI/ReportService2010.asmx?WSDL"
$RS = New-WebServiceProxy -Uri $reportServerURI2010 -UseDefaultCredential
$proxyNamespace = $RS.GetType().Namespace
# Get Schedule Reference
$NeverExpireSchedule= $RS.ListSchedules([System.Management.Automation.Language.NullString]::Value) | where {$_.Name -eq "$NameSharedSchedule"}
$NeverExpireScheduleID = $NeverExpireSchedule.scheduleid;
$NeverExpireDescription = $NeverExpireSchedule.Description;
$NeverExpireDefinition = $NeverExpireSchedule.Definition;
#Write-Host "Found Shared Schedule: '$NameSharedSchedule' with id $NeverExpireScheduleID and definition $NeverExpireDescription";
$NeverExpireScheduleRef =New-Object("$proxyNamespace.ScheduleReference");
$NeverExpireScheduleRef.ScheduleID=$NeverExpireScheduleID;
# Wat dingen voorbereiden
#delivery Extension
#$setting = "Report Server Email"
$matchdata = $NeverExpireScheduleID
$description = "Automatisch ingesteld op " + $NameSharedSchedule
$eventtype = "RefreshCache"
$parameters
#get all needed items
$items = $RS.ListChildren($ReportPathWildCard, $true) | Where-Object {"Dataset" -contains $_.TypeName}
#process all items
foreach ($item in $items) {
$xpath = $item.path
$xtype = $item.TypeName
Write-Host "Processing $xtype $xpath"
$report = $xpath
##SET Cache
$r= $RS.SetCacheOptions( $xpath,[System.Management.Automation.Language.NullString]::Value, $o)
$r= $RS.CreateCacheRefreshPlan( $report,
$description,
$eventtype,
$matchdata,
$parameters
)
}