If memstick images are available then you can use these as directed below.
You can also use FreeBSD-based hybrid ISO files (e.g. FreeBSD-11.1.iso or OPNsense-17.7.5-OpenSSL-dvd-amd64.iso) - see the FreeBSD ISO heading at the end of this page.
Tip: if booting on a headless appliance (i.e. no VGA display), configure the E2B default menu option + 10 second timeout so that your ISO will automatically run from the Main Menu after a 10 second delay.
Versions 9 and 10 of FreeBSD will not boot as an ISO, but the 1.63 version of Easy2Boot and a new MPI Tool Pack v0.044 or later supports FreeBSD 9 and 10 'memstick' images. For GhostBSD, download the .img files and not the .iso files. For MidnightBSD, use the 'memstick' download.
For OPNsense .bz2 downloads for USB drives (e.g. serial download), extract the .img file from the .bz2 file using WinRar or 7Zip and follow the instructions below.
The procedure is to use the MakePartImage process, but as the FreeBSD memstick.img files are already in the correct format for a FreeBSD partition, the .img files don't actually need converting or modifying!:
1. Create a new empty folder on the Windows Desktop (or anywhere else).
2. Drag-and-drop the empty folder onto the MPI_FAT32 MPI Desktop shortcut to make a 30MB (or as small as possible - e.g. 10MB) partition image with no payload. If prompted for a target file, use a filename with either a .imgPTN or .imgPTNA5 file extension - e.g. FreeBSD_10_1.imgPTN or FreeBSD_10_1.imgPTNA5.
Do NOT use a filename that has any dots in it because it will also appear in the E2B Menu - e.g. FreeBSD10.1.imgPTNA5 would not be a good name because the 'FreeBSD10.1' file (see below) would also be visible in the menu!
3. Copy the new .imgPTN file to a menu folder (e.g. \_ISO\LINUX, a 2nd level folder - NOT \_ISO\LINUX\MNU).
4. Copy your FreeBSD memstick .img file to the same folder that the .imgPTN file is in and rename it to match the name of the .imgPTN file but WITH NO FILE EXTENSION - e.g.
FreeBSD_10_1.imgPTN (10-30MB) FreeBSD_10_1 (NO FILE EXTENSION OR DOTS - e.g. 700MB memstick.img file renamed to match with no file extension)
Tip: Download the .xyz (compressed) non-UEFI version, e.g. FreeBSD-10.1-RELEASE-i386-memstick.img.xz and then unzip it to obtain the .img file. The .xyz files are smaller than the .img files. I also tested this with pfSense-CE-memstick-2.3.5-RELEASE-i386.img and OPNsense-18.1.6-OpenSSL-serial-amd64 (1).img.
5. Make all files contiguous on the drive.
6. Use the E2B menu to select the .imgPTN file.
Bug in MPI v0.078 and previous versions:
Do NOT use SWITCH_E2B.exe or you will not get the option to boot from the 3rd partition (was fixed in MPI Tool Pack v0.079+).
Grub4dos can access the files on a FreeBSD type A5 partition just fine as it understands the FreeBSD volume format.
To add more FreeBSD versions to the E2B USB drive, just copy and rename the .imgPTN file (or make a fresh one) and then rename the new FreeBSD memstick .img file to match it.
Note that only 'memstick' images for USB drives will work. Luckily, GhostBSD .img files are in the memstick format.