In Salesforce Plugin, there is no option to configure connection for mutual authentication(2-way SSL). But we have a workaround for achieving the mutual authentication.

Following are the steps to achieve Mutual Authentication:

1)Setup mutual authentication at Salesforce instance. 

2)In Salesforce, if Mutual Authentication is not setup properly then it is difficult to connect to salesforce using Salesforce API's. To check whether mutual authentication is working properly we can use curl command and can refer following url for how to use curl command to test the mutual authentication:
 https://help.salesforce.com/articleView?id=security_keys_uploading_mutual_auth_cert_api.htm&type=5

3)Once the mutual authentication is working properly then please do following:

a)For BW6.x and BWCE: 
In BW Studio, add below properties in VM Argument and when application is deployed on TEA then we need to add it in tra file of appnode:
-Djavax.net.ssl.keyStore=<clientKeystore> -Djavax.net.ssl.keyStorePassword=<password> -Djavax.net.ssl.keyStoreType=<keystoreType>

b)For BW5.x
Add below properties in Application/Desginer TRA file:
java.property.javax.net.ssl.keyStore=<clientKeystore> 
java.property.javax.net.ssl.keyStorePassword=<password> 
java.property.javax.net.ssl.keyStoreType=<keystoreType>

Replace the keystore,password, type with those we want to use at our side.

Steps for implementing 2-way SSL with Salesforce using Salesforce plug-in.

https://help.salesforce.com/articleView?id=security_keys_uploading_mutual_auth_cert_api.htm&type=5