Extract and run IrfanViewPortable. Additional 32 & 64 bit Plugins included.
SaveDir in portable folder: if you don't want: edit IrfanViewPortable.ini.
Settings of installed IrfanView should be preserved.
Extract and run WinSnapPortable.
If you don't want Screenshots in Portable folder, edit WinSnapPortable.ini.
Settings of installed WinSnap should be preserved.