Why would you need to do this? you could have them as optional parameters and then handle within the code. I'm still trying to work out the scenario that this is used. Can you add more information?
Have the proc itself look up the param value(s) based on a control value. That is, add another column to give the parameters table a unique column value, such as identity or a code, then pass that value into the proc so it can retrieve the other param values based on that.
Use the "standard" XML string concatenation to generate the string to exec the proc with parameters from the table, then exec that string.