I had a midarm....which actually was a machine (Viking megaquilter) that was designed as a sit down machine with a larger harp. the feeddogs could be covered, a stitch regulator added, a carriage was mounted on the 10 foot frame. There was a foot pedal but this was not used when the machine was used on a frame and yes, it would be easy to convert this one to a sit-down machine as that is what designed to be in the first place. The longarm I now use is an APQS Lucey with a 26 inch neck. this one is designed to be used on the frame....it only does straight stitch, there is no foot pedal, the speed is controlled by a dial on the machine. the stitch regulator works by monitoring the speed of the wheels as the carriage moves on the frame. This would be difficult to convert to a sit-down machine especially if you wanted stitch regulation. If you would tell us the model of the machine you have, you might get better advice. but I really would consider just getting a machine that is designed for use as a sit-down machine....