2005 Trek 6700 disc 2007 Orbea Onix 2009 Raleigh One Way
Hi. Welcome to Bike Forums. You might want to try posting your question in the 'Training & Nutrition' forum or the 'General Cycling Discussion' forum. I'm not an expert on stationary bikes, however when you get properly fitted for a regular bike, they look at, and adjust, the geometry of the frame, footwear & position of foot on pedal (if you use clipless pedals), etc. This can correct many issues including knock knee.
Try to set it up the same way you would on a real bicycle. There's no difference. Start out by adjusting it using the same rules of thumbs or guidelines for bike fit as everyone else uses. That goes for saddle height, how far forward or rearward the saddle is horizontally, and handlebars. One possible difference is that on a stationary cycle, the goal is to spin, and not to ride long hours or distances, so you get the exercise effects you want quicker (because not too many people want to ride a stationary cycle for hours at a time). Given that you want to spin and not push hard on the pedals (we call that "mashing", here), you may want to set the horizontal position of your saddle at the forward end of the acceptable range, and the saddle a little higher to correspond with that).
The only limiitations are going to be to what extent your stationary cycle allows adjustment of the saddle and handlebar. On some, you may have to settle with as close as you can get it. But it doesn't have to be perfect. Close enough is good enough.