The trio of players who have been fixed up from Honduran champions Motagua, Francisco Ramirez, Reynaldo Clavasquin and Gustavo Fuentes arrived in Scotland late on Saturday night.
Argentinian Fuentes has a Spanish passport, so he could be clear to play in a few days, but the two Hondurans will have to wait until work permits have been obtained.
On Monday evening, the Under-21s are due at Love Street to face St Mirren, though Danny Griffin was still unable to make his return from a knee problem.