Modify open document

hello guyz! is it posible for me to modify an open document such as excel file? what i want to do is modify a particular cell, using 3rd party development tools such as VB6,c#.net, etc.,while the file is open. is it posible? any inputs will be greatly appreciated. Thanks in advance!

No it's not, the Operating System has a duty to prevent this from happening to maintain integrity of the files. :)

Can't you wait though, in a loop, until the resource has been freed up?