AFAIK, you cannot. You'd link the spreadsheet as a table instead if you want to modify it's data - unless you're willing to edit the source file and replace the db object. Many of us here would not store such objects (including pictures) in Access tables. It leads to problems that you don't need, given that there's more reliable ways to link data or images.
For the record, a spreadsheet has columns and rows, where the intersecting space is called a cell. A table has fields and rows, but the intersecting space is seldom referred to as a cell. So it's not clear to me if you're trying to "populate" spreadsheet cells before you open the OLE spreadsheet object or what. Even if you stick with embedded spreadsheets, I would not do so if you intend to modify their data, especially on a regular basis. Embedding the object as a historical record would be somewhat acceptable, but then again, I still would not do so. It's one of those things you can do in Access that many of us wouldn't.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.