Welcome to the community!
Unfortunately, the current version of .NET Micro Framework does not expose any class to access group of pins or the I/O port directly. You'd need to use for example Corey Kosak's SimpleNGen-enabled custom firmware, or implement it using native interop. The Netduino microcontroller has two 32-bit general purpose I/O ports, but only partially broken out (*) - there are two separate groups of 4 consecutive pins available (PWM0 - PWM3 and Analog In 0 - Analog In 3), so you'd need some bit manipulation anyway.
(*) To be compatible with Arduino
I've taught myself a lot in the last couple of weeks, but I haven't gotten that far, yet.
Thanks!