I know how to create Velocity based, and Zone based arpeggios, but I would like to be able to setup a special phrase
that could be controlled using the "Accent Vel Threshold" Param.

If you know how to create Velocity based and Zone Velocity based arpeggios you know most everything you need to know to setup a phrase to trigger at and above a specific Velocity.

That said...
The Accent Velocity Threshold — Determines the minimum Velocity that will trigger the Accent Phrase. Some Arpeggio types include special sequence data called Accent Phrases, which will be played back only when Velocities higher than the specified threshold are received.

Accent Velocity Threshold allows you to trigger a Factory stored data that is associated with a Factory stored Phrase. Those Factory Phrases containing an additional “Accent” Phrase are identified in the DATA LIST Booklet. (There is a column dedicated to Accents.

Typically, found in the factory Drum Arp Phrases, it is used to allow the performer to place an *accent* (Kick drum + Crash cymbal) where/whenever they exceed the velocity value as set.

This is a feature for the factory Phrases.

Program Your Own
If, however, you wish to create an ‘Accent’ that only triggers above a certain velocity: create and then place the ‘accent’ sound in its own Part and trigger it by setting KBD CTRL = On and have its Velocity Limit set so that it is triggered above the threshold you desire.

If it is a simple “punch” (Kick + Crash, like the majority of factory accents) you can simply create that sound in the Part and set a Velocity range...
If, however, you have an entire phrase you wish to initiate, create and assign that User Arp to the customized Part.

If you need it to trigger from any Key, adjust the tuning so the sound remains fixed across all keys. It will sound whenever you exceed the Velocity Low Limit

Thanx very much for the reply. I'm definitely using velocity and zone arps to do what I'm trying to get done. If I could have co-opted The Accent Vel Threshold Parameter for my own user defined arps it would have made things a little more convenient. I was made aware of one of your other very thorough explanations of this feature elsewhere by 5pinDIN which completely answers my question.

Thank you!!

Cheers!