The only thing you could really use that would work anywhere near satisfactorily would be a voltage sensing feeder. (such as Miller 12VS, or Lincoln LN-25). These are both standard feeders, not spool guns. I believe profax sells a control box for their spoolgun that is voltage sensing. Any of these is fairly expensive. TIG & Stick machines are Constant Current machines. This means that they will vary the output voltage in order to try to keep the current at the set level. MIG machines are Constant Voltage which do exactly the opposite: They vary the output current to maintain the set voltage level. Neither type works well for the other, and voltage-sensing feeders are just a work-around for this. If the TIG is that good of a deal, then get it and either stick or TIG the parts. Otherwise, just get a cheap MIG machine either instead of, or in addition to the TIG.