The trimslice will have serious issues with USB disconnects, killing any updates to the _first_ partition on the internal SSD if you have more than one partition (excluding swap).

So, the only reliable way of installing Slackware is with this parition layout:

root@trimslice:~# fdisk -l

Disk /dev/sda: 32.0 GB, 32017045504 bytes
64 heads, 32 sectors/track, 30533 cylinders, total 62533292 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xd8075aa2

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1            2048    42000383    20999168   83  Linux
/dev/sda2        42000384    62533291    10266454   82  Linux swap

Then, make sure you copy bootcmd.txt and bootcmd.sh into the /boot directory after installation finishes. Change directory to "/mnt/boot" and run:
  # sh bootcmd.sh
This will create a boot.scr file which the TrimSlice's U-boot is able to parse.
U-boot is configured to look inside the _first_ partition for a file called "boot.scr". It will look first in the root '/' and then in '/boot'.