That type of control doesn't work in continuous forms, because a continuous form considers all rows in the form's Detail section to be the same row for control purposes. You cannot put a control on the record row because ALL rows are the record row. More specifically, every row of a continuous form is driven from the same definition - the continuous form's design-view detail section, which defines every row to have the same appearance. There IS such a thing as conditional formatting to, for example, alternate colors on rows or to highlight a field in some rows, but that has nothing to do with the "buttons in continuous rows" problem.
You could put buttons on the sub-form in a non-detail section, either a header or footer. Of course, that means when you click something, your cursor is not on a row to be identified. Here is a discussion and sample of some code that would highlight the selected record.
Step-by-step instructions for applying a custom highlight to the currently selected record in a continuous form in Microsoft Access.
nolongerset.com
You could have a click event on a particular field in the continuous form and have that event (which is the same for EVERY ROW) go in to determine which is the form's .CurrentRecord, and there are other ways to deal with that, like have a bound checkbox as a field called "SelectedMe" - and if you click that box, since it is bound, it only affects one record. So you could have it identify the record by the fact of being clicked and then reset the value once you know which row you are looking at. Many ways to skin this cat.