Enabling BitLocker without TPM on MacBook Pro with Bootcamp
I wanted to document this because the information that I've found is spread out and highly complicated. I've found a set of steps that are much simpler to enable BitLocker on a Bootcamp install of Windows. I've combined the information from these two sources for this guide:


How do I mount the EFI partition on Windows 8.1 so that it is readable and writeable?
Bitlocker in Windows 8.1 inside Bootcamp on the MacBook Pro (mid 2009)


The first step is to boot into your Windows partition, then log in, and open up an administrative command prompt.

Mount the UEFI partition to a drive letter:
    mountvol b: /s

Copy the Microsoft EFI binaries to the UEFI partition:
    bcdboot c:\windows /s b: /f UEFI

Unmount the UEFI partition:
    mountvol b: /d

Configure BitLocker to work without a TPM:


Start => run => gpedit.msc
Open the Local Computer Policy node
Navigate to Computer Configuration \ Administrative Templates \ Windows
Components \ Bit Locker Drive Encryption \ Operating System Drives
Double click on Require additional authentication at startup
Enable the feature and check the box next to Allow BitLocker without
a compatible TPM, click Apply and Ok, and close out of Local Group
Policy Editor.


Reboot your machine back to Windows.

You can now enable BitLocker on the device using just a passphrase.