How to become a samma sambuddha (Theravada) If one aspired to being a samma sambuddha, how would the Theravadan tradition advise them to proceed? 

I am familiar with some of the canonical references, (e.g., about getting a prediction from a Buddha) but what steps should one take that would advance that goal in this life?

Thanks!
According to the Buddhist literature, there are 10 perfections (in pali, Paramis) for one to develop to become a samma sambuddha. Everyone who wishes to attain Buddha-hood has to practice these perfections to a specific length of time. Our Gautama Buddha, for instance, had to willingly fulfill the ten perfections in his many existences for an innumerable period of time before being born as "Siddhartha Gautama". 
The ten perfections are as follows:

Perfection of generosity giving
Perfection of Morality
Perfection of Renunciation
Perfection of Wisdom
Perfection of Effort
Perfection of Tolerance
Perfection of Truthfulness
Perfection of Strong Determination
Perfection of Loving-kindness
Perfection of Indifference towards all beings or Equanimity 

Everyone seeking for Buddha-hood has to fulfill willingly all or most of these perfections, each in three different ways, in his every life for a very long period of time until he has already fully possessed all these ten qualities finally leading to Buddha-hood in his rebirth.
However, the time taken to develop these Paramis can vary from Bodhisattvas to Bodhisattvas. There are three types of Bodhisattvas, namely, Intellectual Bodhisattvas Devotional Bodhisattvas and Energetic Bodhisattvas. Intellectual Bodhisattvas take the least amount of time and Energetic Bodhisattvas the most. Our Gautama Buddha was an Intellectual Bodhisattva.