For each product Add to Cart button, add a form and set the product ID accordingly. The product ID is listed next to each product within the Administration Panel > Edit Products.
Here is an example. The required parameters (for products without attributes) are quantity, product, and add.
<form method="get" action="http://www.yourdomain.com/ashop/basket.php">
<input type="hidden" name="quantity" value="1">
<input type="hidden" name="product" value="1">
<input type="hidden" name="add" value="1">
<input type="submit" name="Submit" value="Add to Cart">
</form>
Note: When a form is inserted inside of a table cell, it may cause unwanted enlargement of the table cell and distort the intended page design in some browsers. To avoid this problem, put the <form> and </form> tags between the <tr><td> and the </tr></td> tags.
For example: <tr><form><td> and </tr></form></td>
This is not specifically WC3 compliant, but it works :-)
For quantity selection, substitute a text box in place of the hidden field.
A drop-down selection box can be substituted for to offer only fixed quantities.
<option value="1" selected>1</option>
<option value="2">2</option>
<option value="3">3</option>
<option value="4">4</option>
<option value="5">5</option>
</select>
