if i'm not mistaken, there are two ways getting admission into NIE.
1. you end up being a teacher. you'll be in one of the three courses: degree (BSc/BA), post grad (PGDE) or diploma. you'll be on payroll while on course, except 3rd + 4th year for the Degree course. after that you're gonna serve out the bond. you have to go for a MOE interview and sign a bond first before commencing the NIE course proper.
2. you are free to go after the course. but you have to pay some princely amount for the course - how much it is, i have no idea.