Well, they don't have to appear for the NMLE (Nepal Medical Licensing Examinatin). They can get the registration here is the detail:
Requirement for registration as a foreign national doctor in Nepal Medical Council:-
A filled application in the format of NMC for practice of medicine in a medical college or hospital for stipulated period.
A photocopy of visa and passport attested by a NMC member or any permanently registered doctor authorized for the same.
Any official identity certificate for those who do not require visa/passport must be attested as above in clause (2).
A good standing certificate from the council of the country which domicile country of the applicant.
A recommendation letter for registration with NMC from chief of medical college or hospital.
A letter of recommendation from HMG clearly stating the period and reason for appointment in that particular medical college or hospital.
Clause (6) is not required if the candidate is his/her working hospital or medical college has already done written agreement with HMG for the same or previous consent of HMG has been acquired for any stipulated period.
Mark sheet and certificate of basic degree with internship completion certificate.
Certificate of post graduation if any.
Certificate of registration in other medical council if any.
Details of permanent address and mailing address.
Certificate of post-doctoral training or degree if any.
4 copies of passport size photograph.