Did it when I was younger.  The best way is to be in the lotus position - this is when you see some of the Buddish pictures of diety with their female consort.  You can be hard for hours.  The highest tantra is achieved not by ejaculation but by having all your cell in your body orgasm and explode in ecstacy and bliss.  don't know if tantric providers can do it.  Maybe not the real tantra, but something approximate or a taste of it.

There is a world of difference between actual tantra and the services many providers list as "tantric."  A tantric experience will be one where you feel your soul come alive...whereas you might get a good handjob from some providers listing a "tantric massage."

The trick to sorting the wheat from the chaff is to ask about their training.  A tantrika will not only be willing and able to tell you where she was schooled, but she will often list the lineage of her teachers.

I was fortunate to study under Jan Robinson in Berkeley, CA, and she's got multiple teachers, including Charles and Caroline Muir of the Source School of Tantra.

In actual tantric practice, there is a great deal of information and knowledge you must master before the physical practices can bring any fruit.  And then, there is a great deal of breath training and body awareness exercises.  The first threshold in a man's tantric practice is to master the non-ejaculatory orgasm.  

Once you've got a handle (pun intended) on the non-ejaculatory orgasm, then a tantric massage can become an exercise in exploring the levels of pleasure and energy exchange that naturally ensue.

To the point, I don't know of any actual tantric providers working in NC, but I haven't sampled the ladies of the Tantric Retreat in Asheville (yet).  In fact, all I've done is send emails to some of the women near Raleigh offering "tantric massage" --the ones who appear more legit--and inquired about their schooling. None have replied.