You pretty much solved this one yourself! To write this in T-SQL you right click the Chart Name and change its value to the following expression:
IIF(Fields!chart.Value="110300" AND Fields!division.Value="100","Intercompany AP - USA",IIF(Fields!chart.Value="110300" AND Fields!division.Value="200","Intercompany AP - RUS","Default Chart Name")
See here for explanation on how the IIF function works
From the link you can see that it takes the following format, where commas are used instead of "Then" or "Else":
IIF ( boolean_expression, true_value, false_value )
So to breakdown the expression:
IIF(Fields!chart.Value="110300" AND Fields!division.Value="100",
"Intercompany AP - USA",
IIF(Fields!chart.Value="110300" AND Fields!division.Value="200",
"Intercompany AP - RUS",
"Default Chart Name"
)
)