Untill/if ever chains are implemented serval classes will not be able to max their DPS. With that said, here is a workaround. Its not automatic, so you'll have to set up some MCP buttons.
For Assassins; open your export file and remove stealth requirement from the fallowing spells.
Massacre
Eviscerate
Jugular Slice
Ambush
Stealth Assault
Mortal Blade
Assassinate
Now In you main profile in precast do the fallowing
Masked Strike->Ambush
Then in your cast-stack do your normal rotation minus the a spells you edited.
You'll now need to make two more profiles ChainLong and ChainShort
In ChainLong put the fallowing int the cast-stack (use the order you like)
PFT
Massacre
Eviscerate
Jugular Slice
Ambush
Stealth Assault
Mortal Blade
Assassinate
Fatal Followup
In ChianShort put the fallowing into the cast-stack (use the order you like)
IPS/concealment
Hilt Strike (if concealment to get a hit in)
Massacre
Eviscerate
Jugular Slice
Ambush
Stealth Assault
Mortal Blade
Assassinate
Fatal Followup
Now you'll have to make 3 new MCP buttons.
B1: Main
RawCammand
P1=ProfileConfig:LoadProfile[Main]
B2: ChainLong
RawCammand
P1=ProfileConfig:LoadProfile[ChainLong]
B3:ChainShort
RawCammand
P1=ProfileConfig:LoadProfile[ChainShort]
You'll have to have a timer on FF or someway to know when its ready. Now you can do your chains and control when you do them, you'll actually get better overall DPS our of your assassin, its just not automatic.