If you open it up in SWQL Studio you'll get a preview that suggests the form of XML it's expecting:
If you copy the XML in deviceTemplate and tidy it up, you'll have something like this:
<?xml version="1.0"?><DeviceTemplate xmlns:i="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://schemas.datacontract.org/2004/07/SolarWinds.Orion.Cli.Contracts.DataModel"> <Author/> <AutoDetectType>BySystemOid</AutoDetectType> <Comments/> <Id>0</Id> <IsDefault>false</IsDefault> <Name/> <SystemDescriptionRegex/> <SystemOID/> <TemplateXml/> <UseForAutoDetect>false</UseForAutoDetect></DeviceTemplate>
Most of the elements have string values. Id is an integer. IsDefault and UseForAutoDetect are Boolean values. The possible values for AutoDetectType are BySystemOid and BySystemDescription. The key element for ValidateLogin appears to be TemplateXml. It looks like the TemplateXml is supposed to include details about the device and OID and a series of commands.
<?xml version="1.0"?><Configuration-Management Device="..." SystemOID="..."> <Commands> <Command Name="..." Value="..."/> ... </Commands></Configuration-Management>