That is definiatley feasible. If you utilized square pots you could put 4 plants in 3 Gallon pots with a little bit of room for them to grow horizontally.

The problem with the 3 gallon square pots is that they are taller than round pots so you'll want to implement LST to try to keep the plant short and bushy (plus more main colas.. it's a win win situation all around).

Additionally you'll probably want to run a cool tube in a space that small and a 250w. I say a cool tube because it will allow you more additional height than an air cooled hood or even standard reflector would (plus the obvious need to be able to efficiently cool your space easily). In a 4ft space any vertical space you can reserve for your plants is important.

Good growing. :thumbsup: