To create a Quicken QIF file, start Quicken (yes, it works Wine, and probably Wabi too), choose the menu "File" and select the "Export..." menu entry. Under Quicken Version 3.0, you can only export one account at a time, and thus, exporting will prove to be a tedious process. When exporting, note that there are a series of check boxes marked "Transactions", "Accounts List", "Category List", etc. For best results, you will want to make sure that these three are checked. If you do *not* check the "Accounts List" box, then the name of your account will be lost.
To import a Quicken QIF file, choose the menu "File" and select the entry "Import QIF". The imported wile will be merged with whatever other data you currently have in X-Accountant. This merge allows multiple Quicken accounts to be imported and merged into one account group. Note that during merge, a scan is made for duplicate transactions, and duplicates are removed. A duplicate transaction is one where the date, description (payee), memo, quantity, share price, and debited/credited accounts or categories match exactly. Thus, the merge should be safe unless you have multiple transactions on the same date, to the same account, for the same amount, with the same description and memo.
Note that when the "Accounts List" and "Category List" is exported from Quicken, all accounts and categories will be exported, even if they are empty, and contain no transactions. When these are imported, they will appear as accounts with a balance of zero. If you do not need or use these accounts, delete them. A future X-Accountant enhancement will allow you to delete them en-masse, or to make them invisible without deleting them.