Yes, you can apply for KMTC as a regular student (Government Sponsored Student) with a KCSE mean grade of C (plain). You should however have a C (plain) in Kiswahili or English and C (plain) in Biology. Applications are done online through KMTC Admission portal.
Learn more about KMTC Admission process.
NOTE: Government Sponsored at KMTC does not mean that the government will be pay all your school fees. It only caters for about one third of the fees.