I'm almost sure they could. It would just be a matter of hooking up a thought-based interface on the inside of the head of an unprogrammed robotic body. Andalites controlled their ships using thought-based interfaces, so if they invented it, you can be sure that the Pemalites invented it a few thousand years earlier. The real question is, would the benefits be worth the risk? Keep in mind that the Chee kept their existence a tightly-guarded secret from the Andalites, Yeerks, and humans other than the Animorphs themselves, because they feared what would happen if their technology ever fell into the wrong hands. And rightly so. A Yeerk inside a robotic host would be more powerful than almost any biological creature, with none of the limitations that biology implies. They wouldn't be afraid to die, because they could just build a new body.
And make no mistake, once the Chee gave the Yeerks even one robotic body, the Yeerks WOULD figure out how to build their own. They reverse-engineered the Andalites' technology so fast that they skipped straight from the Stone Age to the Space Age in, like, a week. I give them a couple months before they could reverse-engineer a Chee. In the end, you'd pacify the Yeerks who were just fighting for hosts, sure. But at the cost of giving those power-hungry Yeerks more power than they could possibly imagine. And they might be a minority, but they would then be able to literally BUILD armies. Yeah, I think I see why the Chee never made that move . . .