On this page I'll try to summarize all info on how get PC-BSD boot from USB Flash drive.[[BR]]
'''Create Part'''[[BR]]
1. We need to get USB Flash drive, formatted in FAT with at least 2Gb+ Free space (1,89Gb I have with 7.1 Beta1)[[BR]]
2. We need download DVD-ISO, from [http://www.pcbsd.org/content/view/21/11/]. Yes, we aren't downloading USB or USB-bootonly version.[[BR]]
3. We need to get any ISO extraction tool.  Example: WinRAR [http://www.rarlab.com/download.htm], any Virtual driver (Alcohol, Daemon tools, etc) - mount ISO, and copy - it's the same as extract.[[BR]]
4. Extract content of ISO into Flash drive.[[BR]]
5. Download archive with additional files here [http://javaz.org/soft/pcbsd-usb.zip]. Archive contains two folders, "files", and "syslinux". Extract both these folders somewhere, e.g. C:\pcbsd[[BR]]
6. Go to start menu, "Run" and enter command to run - "cmd". Once you're in command line change directory to where you extracted archive, for example "cd C:\pcbsd\syslinux" You should notice from command line prompt that you are there.[[BR]]
7. Open "My Computer", carefully look for Drive letter of your USB-Flashdrive, make SURE you didn't mistake! When you know drive letter, enter in command line such command, without quotes:  "syslinux -m -a X:" Place correct drive letter instead of X:   If no messages appear, then your USB-Flashdrive made bootable successful! You can now close command line.[[BR]]
8. Copy content of "C:\pcbsd\files" into your USB Flash drive. All these files should be put directly into root of Flash drive, for example file "C:\pcbsd\files\grub.exe" should be copied to "X:\grub.exe", and all others similar.[[BR]]

Yes! We did it! We have our drive.[[BR]]
But not haste boot from it, you should remember additional steps, better you write it somewhere on paper.[[BR]]
[[BR]]
'''Boot Part'''[[BR]]
[[BR]]
1. Make sure you know how boot from USB with your computer. Read some sites would be good.[[BR]]
2. Boot from USB, no additional actions required, and you should see this screen:[[BR]][[BR]]
[[Image(http://javaz.org/manual/1.png)]][[BR]]
3. After short while, you'll see this screen: No actions required too.[[BR]][[BR]]
[[Image(http://javaz.org/manual/2.png)]][[BR]]
4. One-two more seconds, and seem we are stuck with this screen:[[BR]][[BR]]
[[Image(http://javaz.org/manual/3.png)]][[BR]]
You should enter without quotes command "show", and get something like this:[[BR]][[BR]]
[[Image(http://javaz.org/manual/4.png)]][[BR]]
What is important here, is "currdev" value. For me it's "disk0a:"[[BR]]
5. We need to fix this! Enter command "set currdev=disk0s1" and press enter. Remember, if you'll see that in your case currdev isn't "disk0a:", but for example "disk3c'" you must enter command "set currdev=disk3s1". The only important part is "disk" and number.[[BR]]
After this command we must have no error message, like here:[[BR]][[BR]]
[[Image(http://javaz.org/manual/5.png)]][[BR]]
6. Last command! Enter "include /boot/loader.rc" without typos, and after minute-two you'll have started setup of PC-BSD! [[BR]]
Look here, it's kernel loading:[[BR]][[BR]]
[[Image(http://javaz.org/manual/6.png)]][[BR]]

'''Remember, that installing from FAT drive is pretty slow, it could took about hour-two. It should be used on;ly if necessary, like installing PC-BSD to some Netbbok without CD/DVD Drive'''[[BR]]

What was used to make this happen: Some files from Unetbootin, Grub4Dos, Syslinux. Screenshots acquired from Qemu.[[BR]]
Enjoy! [[BR]]