The only way I know, though there will be simpler way that I don't know, is
1/scan in the signature and save the image as bmp., jpeg etc
2/ open the image in Word and save as an HTML document.
On the Tools menu, click Options, and then click the Signatures tab.
To create a signature, click New and then either enter text in the Edit Signature box or click File, and then find the text or HTML file you'd like to use. (The one you have just saved)
Select the Add signatures to all outgoing messages check box.