A table is just a 2D array of strings. Keep it in a shift register and use "replace array element" to modify the desired entry programmatically.
If you want to modify it manually and directly from the front panel, make it into a control and type directly into the desired element. (In this case your program would need to write to it using a local variable).
Atttached is a simple example in LabVIEW 7.0 that shows both possibilities.