According to the documentation, the Lync binary does not offer that feature. However, you could use the Lync SDK to achieve what you want by writing a small helper application (or incorporating the relevant code in your current application).
According to an MVP in the Microsoft forums, this also is not available out-of-the-box.
However, according to the documentation, a PowerShell script like this one should be able to do the trick:
import-module "C:\Program Files (x86)\Microsoft Lync\SDK\Assemblies\Desktop\Microsoft.Lync.Controls.Dll"
$availability = [Microsoft.Lync.Controls.ContactAvailability]::Available
$contactInfo = new-object 'System.Collections.Generic.Dictionary[Microsoft.Lync.Model.PublishableContactInformationType, object]'
$contactInfo.Add([Microsoft.Lync.Model.PublishableContactInformationType]::Availability,
$availability)
$ar = $self.BeginPublishContactInformation($contactInfo, $null, $null)
$self.EndPublishContactInformation($ar)
This script requires the Lync SDK or the Lync SDK redistributable to be installed.
Much of this information has been taken from here.