For an MBA in HR, an LL.B./LL.M would be an added advantage. If you are interested in a full-time course, you can pursue an LL.B. If not, you can opt for an HR-related job and pursue an LL.B. either in an Evening College if your city has one, or go for a correspondence course like BGL or Diploma in Labour Laws & Administrative Laws. I remember Annamalai University offers such correspondence courses; there could be many other universities offering them. You may explore through various websites.
All the best, pal.
Regards,
Kumar S.