Jul 27 - Infinitive vs. gerund in "-ing" participle clauses?

Let's say you have a sentence like this:

Rosa yawned, getting into bed. Rosa bostezó, (meterse/metiéndose) en la cama.

To which tense would the verb "get into" (meterse, I think) be conjugated? When you have any sentence like this, with a participle clause beginning with a gerund, do you conjugate it to the Spanish infinitive or gerund?