Thank you for interest in Syncfusion product.
You can use Mnemonic character for Tabpages[Text property].
For example:
this.tabPageAdv3.Text = "Tab&3";
Please refer the simple sample in the below link which illustrates the above:
http://websamples.syncfusion.com/samples/Tools.Windows/75358/main.htmPlease let me know if this helps.
Regards,
Hema