I have 台灣居民來往大陸通行證 and single entry visa, can I get another single entry at Lowu port of entry?

I have the Taiwanese residence permit but need a visa to enter China while I am in Hong Kong.
I know I can apply for one (takes one day) at a Travel Agency in HK, but heard that I can get it at the border (ie. Lowu) before entering mainland. Is this true?