From services, you can certainly post an XML request as part of the check. That is do-able now.
Arbitrary ports are not available yet.
Regarding devices - there is no mechanism for a collector to tell a remote host to issue a port check. You could fairly easily create a powershell datasource script (for windows) to do this, however.
Something like https://social.technet.microsoft.com/Forums/windowsserver/en-US/7a3304c7-b564-4acc-ab28-2648a20f4bce/telnet-using-powershell?forum=winserverpowershell
I'll add that our datasources dev queue - but you should be able to script it from there, if impatient.
