The following code works for me… no need to prompt for username/password 🙂
<File Id='JobServiceEXE' Name="JobService.exe" DiskId='1' Source="JobService.exe" KeyPath="yes"/>
<ServiceInstall
Id="ServiceInstaller"
Type="ownProcess"
Name="JobService"
DisplayName="123 Co. JobService"
Description="Monitoring and management Jobs"
Start="auto"
Account="[SERVICEACCOUNT]"
Password="[SERVICEPASSWORD]"
ErrorControl="normal"
/>
<ServiceControl Id="StartService" Start="install" Stop="both" Remove="uninstall" Name="JobService" Wait="yes" />
</Component>