The OC object method cannot be used in Labtalk script. However, you can try using the following script to set colored text to cells. Please note that the first three lines of the script are used to set the worksheet cells to be rich text.
wproperties execute:=get iotrgui:=tr;
tr.TextControl.OriginTextControl=1;
wproperties execute:=set iotrgui:=tr;
col(A)[1]$ = "\c2(A)-\c3(↑)-\c4(↓)";
James