有限公司因虧損嚴重而不能支付員工薪金

The only way is to appeal.

Something does not sound right in this case. As an limited company, directors/shareholders can't be held responsible. So it sounds strange than when the Tribunal orders the directors/shareholders to pay.

It sounds like the original summon contains fatal errors which has grounds for an appeal.

See here for detail:

http://www.judiciary.gov.hk/tc/crt_services/pphlt/html/labour.htm#4

公司現今可行之法是申請破產.因為公司是屬於有限公司,董事不須為欠薪而動用私人財產(當然若講道義,可以動用個人資產用以清還欠薪)
公司於破產清盤後,依法庭判決,將清盤後拍賣所得用以清還各項欠債.員工如領不到欠薪,可由勞工處安排申領破產基金,(有規定限額)