I don't believe that there is any direct way to convert parameter estimates obtained from the MIANALYZE procedure into standardized parameter estimates. However, you could use a process as described below to obtain standardized parameter estimates:
1) impute data using PROC MI
2) standardize the response and predictors to have mean 0 and variance 1 using PROC STANDARD
3) fit the regression model to each of the standardized imputation data sets outputting parameter estimates and the covariance matrix of the parameter estimates. Any of a number of procedures could be used for this step.
4) Combine standardized regression coefficients from each imputation set into a single estimate of the standardized regression coefficients using PROC MI