Firstly, the ebay 3 phase inverter controller; The SET control bus has the following connections;
5v; Control voltage, connect to one terminal of your pot
Signal; 0-5v pulsed output indicating speed of driver
Z/F; Direction. 5V=clockwise, 0V=anticlockwise
VR; Input voltage 0 - 5v. Connect this to the variable wiper of your pot
GND; 0v, connect this to the the other terminal of your pot.
I have experimented with it - it gives quite good control.
Secondly; I looked at your Sabretooth motor controllers. They are all for brushed motors. They cannot be used for 3 phase brushless motors.
Thirdly; I have recently gone through a learning curve of 3 phase brushless motors, so I thought I would give a summary of my lessons learnt. My apologies if this is trivial;
Small brushless motors are in the R/C hobby universe. They have incredible power density and efficiency and have grown from hobby model plane, boat and copter demands.
The brushless motor controllers (or ESC) are also hobby R/C orientated. They are driven by the R/C servo signal protocol. This protocol is a 0-5v pulse strobed every 20mS. the pulse varies from 0.6mS (0% travel) to 2.4mS (100% travel).
If you want to convert from 0(0%)-5v(100%) potentiometer to R/C servo signal (pulsed as above) you will need to do some programming (any microprocessor, but the PICAXE controller can achieve this with a just a few commands) or buy a convertor.
An alternative to a hobby R/C ESC with pulsed control is to use an 3 phase inverter controller with an alternative control signal like the ebay one above.
The hobby R/C ESC controllers are always your best bet. They are a mature technology, compact, efficient and cheap. However, if you buy them off ebay or an online hobby shop you will be faced with poor documentation and a horrible programming methods. You have to match the ESC to your motor, and only a few ESC’s are forward and reverse.
Your real best bet is to buy the hobby R/C ESC off a reputable supplier who has filtered the quality, documentation, programming and matched it to your motor. So, unless you want a lot of hassle, I suggest you buy the BlueRobotics Basic ESC.