The act of "dowsing in" is essentially searching for something, typically in a methodical manner. There are several synonyms that can be used instead of "dowse in" to convey a similar meaning. For example, "comb through" can be used when searching for something in a meticulous and thorough manner. "Scour" is another synonym that can be used to mean "to search" or "to hunt for" something. "Sift" is a more subtle synonym which suggests separating one thing from another, as in finding specific information. Other related synonyms include "peruse", "rummage", "hunt", "delve" and "probe." Ultimately, the choice of synonym will depend on the context and the level of detail required in the search.