ok, fired up shake and checked the manual (page 606 is what you want) and found something much more elegant:
CODE
SFileIn1 = SFileIn("/path/FILE1_NAME", "Auto",
0, 0, "v1.1", "0", "", 0);
SFileIn2 = SFileIn("/path/FILE2_NAME", "Auto",
0, 0, "v1.1", "0", "", 0);
Select1 = Select(Step(0,2@1), SFileIn1, SFileIn2, 0);
AddText1 = AddText(Select1, Select1.branch==1?"{SFileIn1.imageName}" : "{SFileIn2.imageName}",
"Utopia Regular", 20, xFontScale/GetDefaultAspect(), 1, width/2,
height/2, 0, 2, 2, 1, 1, 1, 1, 0, 0, 0, 45, 0, 1);
just leaning all this stuff myself 
++ christoph