First of all, APRS & Packet are 2 separate modes, and thus require separate softwares. Also, you cannot run both at the same time with only one radio and Signalink.
I concur with AGWPE to operate the Signalink. It makes the Siganlink operate as a virtual TNC. But, you will need additional software for APRS & Packet. Suggestions are UI-View32 for APRS, and Outpost Packet Message Manager for Packet. I am going to provide several links below, but you are going to have to go through a reading and learning process, because setup is not for the faint of heart.
AGWPE - http://www.sv2agw.com/downloads/
Sound Card Packet - http://www.soundcardpacket.org/
(A setup guide.)
UI-View32 - http://www.apritch.myby.co.uk/uiv32_uiview32.php?lang=english
UI-View32 set up notes and modifications - http://www.wa8lmf.net/aprs/UIview_Notes.htm
(UI-View32 needs several things done to "moderize" it, read very carefully!)
Outpost Packet Message Manager - http://www.outpostpm.org/
(Download and setup info.)