Piyush, if you are not from MP, but want to appear for MPPSC, you can subjective to the eligibility criteria mentioned in their oficial website at: http://www.mppsc.nic.in/Rules/Eligibility.html . Any Indian National who meets the eligibility criteria can appear for MPPSC. Having said that the reservation policies are appllicable for Candidates who hold the domicile of MP and not out of the State Candidates. You will be considered as Unreserved if you do not belong to MP. The GO states and we quote:

"The various concessions given in the advertisement, for the candidates of Scheduled Castes, Scheduled Tribes and Other Backward Classes shall be applicable only to those who are domiciled in Madhya Pradesh and belong to Scheduled Castes and Scheduled Tribes notified as such by the Government of Madhya Pradesh and to Other Backward Classes recognized by the Madhya Pradesh Government. Scheduled Caste, Scheduled Tribe and O.B.C. candidates of other states will be considered as belonging to unreserved category. Reservation, relaxation in age limit and other benefits will not be allowed to the candidates belonging to the 'creamy layer' of the Other Backward Classes recognized by the Government of Madhya Pradesh". You can check that here: http://www.mppsc.nic.in/exam_2012/psc%20rules%20in%20english.pdf