Yes you can do arms and legs ME in the same day. For XC skiing the best LME upper body workout is poling in more difficult conditions. Most specific: Double or single pole uphill on roller or snow skis. In the gym use the lat pull down machine and do standing double pole pull downs.
A roller borad is great for this. A C2 Skierg works well but its hard to add enough resistance for true LME work.