In case you have purchased the goods from a dealer/importer and the dealer's/importers invoices does not bears the following remarks : -
" no credit of the additional duty of customs levied under sub-section (5) of section 3 of the Customs Tariff Act, 1975 shall be admissible"
then you can take the Cenvat Credit of ACD. Non mentioning of this remark means importer is not applying for any refund and is passing on the cenvat benefit.
As per notification No. 102/2007 - Customs. refund of ACD will only be available to importer, if conditions therein are fulfilled. This is condition No. b of said notification.