I want to use a CD 4007 inverter as 3 PMOS transistors. Pin 7 must be -Vdd, can this pin still act as a drain?

Question

The data sheet can be found here
http://www.datasheetcatalog.com/datasheets_pdf/C/D/4/0/CD4007.shtml

I'm trying to use this chip for a current mirror with three PMOS

Answer 1

You seem to have some confusion between the meaning of Vss and Vdd. Vdd is the most positive voltage and is connected to the source of one of the PMOS devices in addition to all the substrates of the PMOS devices. Since the drain of a PMOS device must be lower than its substrate, it's the sources that must be connected to the most positive voltage. I suggest that you review:
http://en.wikipedia.org/wiki/MOSFET