Default keyboard shortcut is Alt+P. You can change this in
"Options">"Menu Setup">"Tools">"TpX drawing tool"
Typing Alt+P in a TeX document with included TpX drawings will run TpX.exe and load a drawing into it. The drawing closest to the current cursor position will be opened. The TpX file containing drawing need not exist.
WinEdt is a powerful editor and shell for TeX documents.