I will try to answer this, but you're probably not going to love the answer.
Lets start with the basics. If your ACIM is designed for 200V AC at 50Hz, that roughly equates to 282V DC at 50Hz.
You only have 150V, so your fweak should be 150 / 282 * 50 = 26.6Hz. Looks like you calculated this correctly
Next, you will need some boost. This can be calculated from the DC resistance of the motor and your desired peak current, but it's probably easier done by trial and error. Start at boost=0 and increase in small increments until the motor actually works, and then continue to increase until torque is roughly consistent from a standstill up to 25Hz. More boost = more current and torque at 0RPM. You'll probably find you need to increase it into the 4-digits range (1000+) but start low and be cautious with it.
I'm not aware of any way to calculate slip, but as a starting point, I would suggest using the rated slip as fslipmin, which is probably around 3% of 50Hz (fslipmin=1.5) and fslipmax to be double that (fslipmax=3).
fslipconstmax is a higher slip value to be used at speeds above fweak, and fconst is that frequency at which that higher maximum slip should be reached. For example: if you set fweak=26, fconst=50, fslipmax=3, fslipconstmax=5, then what will happen is you will get a slip of 3Hz up to 26Hz, but then this will increase proportionally from 3Hz at 26Hz up to 5Hz at 50Hz. This helps to overcome back EMF and produce more torque at higher speed.
I hope this all makes sense. Ultimately, there are very approximate starting points, and you will likely wish to push the motor a lot harder than its rated values.