Hi Morgol,
The XSPICE engine built into Multisim manages the low-level and event-driven capabilities and co-simulates it with the traditional analog SPICE engine. It does not contains any interpreters or compilers for high level specification of functionality. In the past years some additional development was made to build layers on top of XSPICE for higher level functionality such as what MultiMCU (now Multisim MCU module) and MultiVHDL were. MultiVHDL however was licensed from a 3rd party and it became overwhelming and difficult to maintain, to improve and to support. We had to drop it and start looking for alternate solutions. There are many options but we want to do something permanent, supportable and efficient to integrate with the engines so is not an easy pick or thing to do.
Answering your question, trying to do in XSPICE what you wanted to do in HDL or Verilog would be absolutely time-consuming and extremely difficult to accomplish, the current engine is not prepared to give you any aid on doing it. Is definitely not recommended.
Nestor
