Okay, I may forget the exact procedure when setting up
BitLocker. But, there is a point where BitLocker ask to
test your setup (TPM or USB stick), I believe you can actually
skip that and continue on with encryption. And, just in case-
there is an option to generate a very long PIN/password, save it
write it down and print it out.
Did you enable BitLocker to be used without TPM,
by the way?
run>gpedit.msc>Computer Configuration>Administrative Templates>
Windows Components>BitLocker Drive Encryption,
Control Panel Setup: Enable advanced startup options
Set that to Enabled.
Go back to Control Panel, BitLocker options.
You will now have the choice to use BitLocker
without TPM. And just use a USB stick with the
key stored on it.
During the activation of BitLocker, it will, IIRC,
want to reboot to test your USB stick. I'm pretty
sure that can be skipped.
After the encryption, go back to BitLocker's settings
and "turn off" Bitlocker but do not chose the "Decrypt"
option.
-Michael