@jack290:
As a linux user, the way I've got round this is to connect the SSD into a linux system and partition the disk using the linux fdisk.
I found that when installing, the PFS installer gets upset if the partitions are not aligned on what it thinks is a cylinder boundary, and I find the way round this is to choose sectors which align with both 63 (the old cylinder system) and also 4K boundaries. This requires a little use of a calculator. There is usually plenty of room on an SSD, hence I align to 63 x 4096 boundaries, ie 258048.
Typically,
start 4644864 ( 18 x 258048) finish 30965759 ( (120 x 258048) -1 ) is 26320896 sectors, 12.5Gb
Mark the partition as bootable and set a free BSD type (a5). More partitions can be created by the same method. The partition marked bootable must be used.
Put the disk in the PFS box and install.
When installing, choose own partitioning, pick this partition, do not format then install the bootblocks (bootloader) and complete the install.
EDIT - BSD calls partitions slices. The above should read "do not slice the disk, pick the slice (partition) you created." I'm working from memory so I hope there is enough here for you to get started.
The above is a somewhat blunt approach which works for me because I am familiar with the linux version of fdisk. It is not much help if you do not have an available linux box to use. Someone else may offer a better solution, if you are familiar with the BSD version of fdisk it should be possible to boot the installer to a command line, fire up the BSD partitioner and then use the approach given above to set the partition start and end points. ( I'm not familiar with the BSD version of fdisk and it may insist on cylinder boundaries, however a little use of a calculator should still allow the problem to be solved.)
There are differing views on whether or not to set trim, if you want to do so, after installing, boot to a command prompt at the first menu and run:-
/sbin/tunefs -p / and
/sbin/tunefs -t enable /
to enable trim.
Hope some of this helps, and I might add that 4k is also preferred for many modern spinner disks which use "advanced format".
I just do a 16MiB alignment. No thinking involved then and only wastes a minuscule amount of space.