OK, I could find it by myself.
For anybody out there looking for similar solution:
for (int ii=0; ii<dsRange.GetSize(); ii++)
{
TreeNode trCheck = testTree.Multi.AddNode("dp" + ii, TRGP_CHECK);
trCheck.SetAttribute(STR_LABEL_ATTRIB, dsRange[ii]);
trCheck.nVal = 1;
trCheck.SetAttribute(STR_ATTRIB_HANDLER_RC, Dialog_Event)
}