Sometimes "temp" spots are available early or late in the summer for 10 days or so, particularly if some previously committed players are busy with conference playoffs or the CWS in early June. Could your player ask for a temp spot somewhere? Where are his teammates going? Sometimes those temp spots stick if the coach is impressed or has a need.
Also, some leagues prefer players who are freshmen (e.g. some Futures League teams), others prefer older players, and others only take local players (or players with their own transportation), so I think you need to ask around. I do think his coach is going to need to refer him at some point; it is hard to imagine a summer coach accepting a player without input from the College coach.