In a seated position? Sure! If you have an illness etc that hinders your chances....
We can do salat while riding in some situations (which is technically seating)...
The purpose of salat is to Remember/contact God (2014).... We can do Salat while walking, riding, standing, bowing..... that does not change its purpose of remembering/contacting God...
As for hand position during supplication (dua), there is a position cited in the Quran
"To Him alone is the supplication of truth. And those they call upon besides Him do not respond to them except as one who stretches his hands toward water to reach his mouth, but it will not reach it . And the supplication of the disbelievers is but in vain . (1314)
As for salat, this would be my approach,
(Part 1 Positions & How many Rak'a?)
http//www.youtube.com/watch?v=OzoaS43fOew&feature=plcp
(Part 2 Prerequisites, Manners, and what to say)
http//www.youtube.com/watch?v=ZOzex4NRl_s&feature=plcp
(Part 3) How Many Salats Are there? 3 Salat Theory)
http//www.youtube.com/watch?v=4MX7Diab4Tg&feature=plcp
Also see http//www.quran-islam.org/main_topics/islam/pillars/al-salat_(P1192).html
http//www.detailedquran.com/quran_data/Salaat%20in%20the%20Quran.htm
(also look around the Quran-islam.org website for other articles
Recommended readings
Why language is irrelevant!
http//free-minds.org/forum/index.php?topic=9603266.0
The Original purpose of our creation
http//free-minds.org/forum/index.php?topic=9603282.0
God's System of Righteousness (The Reward system for those who are Nice/Benevolent)
http//free-minds.org/forum/index.php?topic=9602900
God's Systems of Guidance and Misguidance
http//free-minds.org/forum/index.php?topic=9603904.0
7 "Hells", 2 Heavens, and a "Purgatory"
http//free-minds.org/forum/index.php?topic=9603259
~ God's Unconnditional servants ~
http//free-minds.org/forum/index.php?topic=9603053