Import Certificate installed in browser to sign a document digitally and encrypting the excel file

I had an project in which the documents were digitally signed using .pfx files but now with the change in requirement, the organisation uses E-Tokens( usb devices), which when plugged in the computer, installs certificates into the browsers, now i need to digitally sign the pdf file and encrypt the excel file as, the digital signature is of class 3, signing and encryption both, signing for pdf file and encryption for excel file.

Can any one help me with a way on how to import the certificate installed in browser and den use the keys to sign and encrypt the excel file.

via Chebli Mohamed