How could I post custom tweets on my twitter account using vb.net?
If is not possible, which I doubt, is there any way to achive this with c# or javascript?
You can use the twitterizer library.
Here's an example how to use it:
Dim tokens As New OAuthTokens()
tokens.AccessToken = "XXX"
tokens.AccessTokenSecret = "XXX"
tokens.ConsumerKey = "XXX"
tokens.ConsumerSecret = "XXX"
Dim tweetResponse As TwitterResponse(Of TwitterStatus) = TwitterStatus.Update(tokens, "Hello, #Twitterizer")
If tweetResponse.Result = RequestResult.Success Then
' Tweet posted successfully!
Else
' Something bad happened
End If
BTW, here's a list of avaiable twitter libraries (but it's not 100% up-to-date).