The t statistic is the ratio of the estimate to its standard error. If you can determine the standard error, you can take this ratio yourself.
However, least squares is the maximum likelihood method for a regression if the residuals are normally distributed. In that case you can let regress (or regstats or LinearModel) compute the coefficients and t statistics for you. If you have some other estimation method that is not least squares, you would need to determine the standard errors of those estimators.