Version 4 allows for import of .smi and .sdf files (<Input> tab, <Chemical List> group, <List> button). However, .smi files with CAS only will not be accepted. Here's an excerpt from the help file:
"A set of chemicals could be loaded via a list with specified atom connectivity stored in a file. Currently supported by the system atom connectivity file formats are SDF and SMI. Files with SMILES may contain TAB delimited CAS number and chemical name followed by the corresponding SMILES string. Usually the extension of these files is *.smi.
In addition, you have an option to load a file from the last used folder or from Toolbox example files"