Are they the same as, or similar to, massage therapists? A quick google search found this:
http://www.mauiwellness.com/
It is a type of massage. Massage therapists can train in any number of modalities and lomi lomi is a style of traditional hawaiian massage which uses long flowing strokes.
There are so many styles of massage: Sports, Remedial, Swedish, Thai, Chinese, cranio sacral therapy, acupressure - the list goes on.
IMO its important to choose a therapist who is a fully qualified and accredited massage therapist first and specialises in lomi lomi second (if that is the style you want to try).
Avoid those people who have spent a couple of week-ends doing a course to learn lomi lomi and have no other medical training. Also, make sure the practitioner has insurance and takes a full medical history from you.