Yes, it's possible to associate file types with programs in Windows.

Control Panel > Programs > Default Programs > Set Associations
Change .SEQ to open with x:\RealBand.exe

Attached Files (Click to download or enlarge) (Only available when you are logged in)
2016-04-02_07-49-01.jpg (114.41 KB, 27 downloads)

BIAB & RB2025 Win.(Audiophile), Sonar Platinum, Cakewalk by Bandlab, Izotope Prod.Bundle, Roland RD-1000, Synthogy Ivory, Kontakt, Focusrite 18i20, KetronSD2, NS40M Monitors, Pioneer Active Monitors, AKG K271 Studio H'phones